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BTEB Diploma in Engineering Semester Final Examinations study materials
BTEB Diploma in Engineering Semester Final Examinations study resources

BTEB Diploma in Engineering Semester Final Examinations practice questions

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Question 1Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In a four-stroke diesel engine, during which stroke is air compressed to a high pressure and temperature?

  1. Exhaust stroke
  2. Compression stroke Correct answer.
  3. Power stroke
  4. Intake stroke

Explanation

The compression stroke closes both valves and reduces cylinder volume, raising air temperature above the fuel's ignition point. Fuel is injected near the end of this stroke so it ignites spontaneously without a spark plug.

Question 2Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

Which instrument is used to measure the current flowing through a circuit branch without breaking the circuit?

  1. Wattmeter
  2. Megger
  3. Clamp meter Correct answer.
  4. Voltmeter

Explanation

A clamp meter has a split core that senses the magnetic field around a conductor, so it reads current without disconnecting anything. Its jaws encircle the wire and the induced signal is proportional to the load current.

Question 3Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The main purpose of adding coarse aggregate to a concrete mix is to:

  1. Provide a strong, hard filler that reduces shrinkage Correct answer.
  2. Accelerate the setting time of cement
  3. Increase the workability of the wet mix
  4. Act as a lubricant between fine particles

Explanation

Coarse aggregate forms the structural skeleton of concrete, giving it strength and stiffness while occupying most of the volume. Using graded coarse aggregate also reduces the paste content and hence drying shrinkage.

Question 4Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In a computer, which component permanently stores the firmware that starts the machine when power is applied?

  1. Cache memory
  2. Hard disk drive
  3. RAM module
  4. ROM chip Correct answer.

Explanation

The basic input/output system firmware is held in non-volatile read-only memory so it survives power loss. On start-up the processor fetches instructions from this chip to initialise hardware and load the operating system.

Question 5Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A simply supported beam carries a central point load of 20 kN over a span of 4 m. What is the maximum bending moment?

  1. 80 kN·m
  2. 40 kN·m
  3. 10 kN·m
  4. 20 kN·m Correct answer.

Explanation

For a central point load the reactions are each half the load, giving 10 kN at each support. The maximum moment occurs at midspan and equals reaction times half the span, that is 10 kN multiplied by 2 m, giving 20 kN·m.

Question 6Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

Three resistors of 6 Ω, 3 Ω and 2 Ω are connected in parallel. What is the equivalent resistance?

  1. 1 Ω Correct answer.
  2. 0.5 Ω
  3. 11 Ω
  4. 3 Ω

Explanation

For parallel resistors the reciprocals add: one sixth plus one third plus one half equals one. The reciprocal of that sum is therefore 1 Ω, which is smaller than the smallest branch resistance as expected.

Question 7Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A shaft transmits 15 kW at 300 rpm. Taking π as 3.14, the torque on the shaft is approximately:

  1. 0.477 N·m
  2. 4 770 N·m
  3. 477 N·m Correct answer.
  4. 47.7 N·m

Explanation

Power equals torque multiplied by angular velocity, and angular velocity is 2πN/60. Substituting 15 000 W and 31.4 rad/s gives torque of about 477 N·m.

Question 8Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

Which type of foundation is most suitable for a multi-storey building on soft clay with a very deep firm stratum?

  1. Pile foundation Correct answer.
  2. Raft foundation
  3. Strip footings
  4. Isolated spread footings

Explanation

Piles transfer structural loads down through weak clay to a deeper bearing stratum by skin friction and end bearing. When the firm layer is far below ground, shallow foundations cannot control settlement economically.

Question 9Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In a binary system, the decimal number 45 is represented as:

  1. 100101
  2. 110101
  3. 101101 Correct answer.
  4. 101011

Explanation

Powers of two summing to 45 are 32, 8, 4 and 1. Placing ones in those positions from 32 down to 1 gives the bit pattern 101101.

Question 10Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A transformer has 200 turns on the primary and 50 turns on the secondary. If the primary voltage is 400 V, the secondary voltage is:

  1. 50 V
  2. 1 600 V
  3. 100 V Correct answer.
  4. 200 V

Explanation

The voltage ratio equals the turns ratio, so secondary voltage is primary voltage multiplied by secondary turns over primary turns. That is 400 V times 50/200, giving 100 V for this step-down transformer.

Question 11Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The main function of a fuse in an electrical circuit is to:

  1. Melt and open the circuit under excessive current Correct answer.
  2. Convert alternating current into direct current
  3. Limit the current to a fixed value during normal operation
  4. Improve the power factor of the load

Explanation

A fuse contains a calibrated element that melts when current exceeds its rating, breaking the circuit and protecting conductors and equipment. It acts once and must be replaced after operation.

Question 12Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

Which thermodynamic cycle is the ideal reference cycle for a spark-ignition petrol engine?

  1. Diesel cycle
  2. Brayton cycle
  3. Otto cycle Correct answer.
  4. Rankine cycle

Explanation

The Otto cycle adds heat at constant volume, matching the near-instantaneous combustion of a premixed petrol-air charge. Its efficiency depends on compression ratio and specific heat ratio.

Question 13Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The process of heating steel to a suitable temperature, holding it, and then cooling slowly in the furnace is called:

  1. Case hardening
  2. Normalising
  3. Tempering
  4. Annealing Correct answer.

Explanation

Annealing softens steel, relieves internal stresses and refines grain structure by slow furnace cooling. The slow cooling allows carbon to diffuse and form equilibrium microstructures.

Question 14Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In surveying, a benchmark is best described as:

  1. The line joining two points of equal elevation
  2. A permanently fixed point of known reduced level Correct answer.
  3. The horizontal angle measured between two staff positions
  4. A temporary point set up for a single instrument reading

Explanation

A benchmark is a stable reference whose reduced level has been accurately determined, usually from a national datum. Surveyors start and close level runs on benchmarks to control cumulative error.

Question 15Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A pump lifts water through a total head of 20 m at a discharge of 0.02 m³/s. Taking water density as 1 000 kg/m³ and g as 9.81 m/s², the water power is approximately:

  1. 392 kW
  2. 0.39 kW
  3. 39.2 kW
  4. 3.9 kW Correct answer.

Explanation

Hydraulic power equals density times gravitational acceleration times discharge times head. Multiplying 1 000 by 9.81 by 0.02 by 20 gives about 3 924 W, or roughly 3.9 kW.

Question 16Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In an n-p-n transistor operating in the active region, the base-emitter junction and base-collector junction are respectively:

  1. Forward biased and reverse biased Correct answer.
  2. Reverse biased and forward biased
  3. Both forward biased
  4. Both reverse biased

Explanation

Normal amplification requires the emitter junction to inject carriers, so it is forward biased. The collector junction is reverse biased so injected carriers are swept into the collector region.

Question 17Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A mild steel specimen of original length 50 mm is stretched to 50.5 mm. Its percentage elongation is:

  1. 0.5 %
  2. 1.0 % Correct answer.
  3. 10.0 %
  4. 5.0 %

Explanation

Elongation is the change in length divided by original length, multiplied by one hundred. The change is 0.5 mm over 50 mm, which is 0.01, or 1.0 percent.

Question 18Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

Which addressing mode specifies the operand inside the instruction itself?

  1. Direct addressing
  2. Indexed addressing
  3. Immediate addressing Correct answer.
  4. Indirect addressing

Explanation

In immediate addressing the operand value is encoded in the instruction word, so no memory fetch is needed for the data. This makes it fast but restricts the operand size to the available field.

Question 19Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A three-phase induction motor has a synchronous speed of 1 500 rpm and runs at 1 440 rpm. Its slip is:

  1. 0.96
  2. 0.06
  3. 4.0
  4. 0.04 Correct answer.

Explanation

Slip is the difference between synchronous and rotor speed divided by synchronous speed. The difference is 60 rpm, and 60 divided by 1 500 gives 0.04, or four percent.

Question 20Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The circular curve element that is the straight distance from the point of intersection to the tangent point is called the:

  1. Tangent length Correct answer.
  2. Mid-ordinate
  3. Apex distance
  4. Long chord

Explanation

Tangent length is measured along the original straights from the intersection point to where the curve begins. It equals the radius multiplied by the tangent of half the deflection angle.

Question 21Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A simply supported rectangular beam has a width of 200 mm and an effective depth of 400 mm. Its section modulus about the bending axis is:

  1. 8.00 × 10⁶ mm³
  2. 2.67 × 10⁶ mm³
  3. 5.33 × 10⁶ mm³ Correct answer.
  4. 1.07 × 10⁷ mm³

Explanation

Section modulus for a rectangle is width times depth squared divided by six. Substituting 200 mm and 400 mm gives 200 times 160 000 divided by six, about 5.33 million cubic millimetres.

Question 22Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A 10 kΩ resistor and a 10 kΩ resistor form a voltage divider across a 12 V supply. A load of 10 kΩ is connected across the lower resistor. The output voltage becomes approximately:

  1. 8.0 V
  2. 3.0 V
  3. 6.0 V
  4. 4.0 V Correct answer.

Explanation

The load in parallel with the lower 10 kΩ resistor gives 5 kΩ. The divider then outputs 12 V times 5 kΩ over the sum of 15 kΩ, which is 4 V.

Question 23Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In a vapour compression refrigeration cycle, the component that rejects heat to the surroundings is the:

  1. Expansion valve
  2. Condenser Correct answer.
  3. Compressor
  4. Evaporator

Explanation

The condenser receives high-pressure superheated vapour from the compressor and removes heat so the refrigerant liquefies. The rejected heat equals the refrigerating effect plus the compressor work input.

Question 24Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A hydraulic press has a small piston of area 20 cm² and a large piston of area 500 cm². If 100 N is applied to the small piston, the force available at the large piston is:

  1. 4 N
  2. 2 500 N Correct answer.
  3. 25 000 N
  4. 250 N

Explanation

Pascal's law gives equal pressure throughout the confined fluid, so force scales with piston area. The area ratio is 500 over 20, which is 25, and 25 times 100 N gives 2 500 N.

Question 25Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A 8-bit successive approximation analogue-to-digital converter has a full-scale input of 5.1 V. Its resolution is approximately:

  1. 10 mV
  2. 40 mV
  3. 5 mV
  4. 20 mV Correct answer.

Explanation

An 8-bit converter divides full scale into 255 equal steps. Dividing 5.1 V by 255 gives about 0.02 V, or 20 mV per least significant bit.

Question 26Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The SI unit of electric charge is the:

  1. volt
  2. ohm
  3. ampere
  4. coulomb Correct answer.

Explanation

Electric charge is measured in coulombs, where one coulomb is the charge transported by a current of one ampere in one second. The ampere measures current, the volt measures potential difference, and the ohm measures resistance.

Question 27Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In a four-stroke diesel engine, the fuel is injected into the cylinder during the:

  1. middle of the power stroke
  2. beginning of the intake stroke
  3. end of the exhaust stroke
  4. compression stroke near top dead centre Correct answer.

Explanation

In a diesel engine, air is compressed to a high pressure and temperature, and fuel is injected near the end of the compression stroke, just before top dead centre. The heat of compression ignites the fuel, starting the power stroke.

Question 28Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The main constituent of ordinary Portland cement that provides early strength is:

  1. tricalcium silicate Correct answer.
  2. tetracalcium aluminoferrite
  3. tricalcium aluminate
  4. dicalcium silicate

Explanation

Tricalcium silicate hydrates rapidly and is the principal compound responsible for the early strength development of Portland cement. Dicalcium silicate contributes mainly to later strength, while the aluminate and ferrite phases affect setting and durability.

Question 29Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In a computer, the arithmetic logic unit (ALU) is responsible for:

  1. managing input and output devices
  2. storing the program instructions permanently
  3. controlling the sequence of instruction execution
  4. performing arithmetic and logical operations Correct answer.

Explanation

The ALU is the part of the CPU that carries out arithmetic operations such as addition and logical operations such as AND, OR, and comparison. It works on data supplied from registers under the control of the control unit.

Question 30Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The minimum number of satellites required for a GPS receiver to determine a three-dimensional position (latitude, longitude, and altitude) is:

  1. two
  2. three
  3. four Correct answer.
  4. six

Explanation

A GPS receiver measures the travel time of signals from satellites to compute ranges. To solve for three position coordinates and the receiver clock offset, at least four satellites are needed.

Question 31Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The property of a fluid that measures its resistance to gradual deformation by shear stress is called:

  1. compressibility
  2. surface tension
  3. viscosity Correct answer.
  4. density

Explanation

Viscosity is the internal friction of a fluid that resists shear deformation; a fluid with high viscosity flows less readily. Density is mass per unit volume, surface tension arises at liquid interfaces, and compressibility measures volume change under pressure.

Question 32Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The binary equivalent of the decimal number 13 is:

  1. 1001
  2. 1101 Correct answer.
  3. 1011
  4. 1110

Explanation

Repeated division of 13 by 2 gives remainders 1, 0, 1, 1 from least to most significant bit, so the binary form is 1101. Checking: 8 + 4 + 1 = 13.

Question 33Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In engineering drawing, a line drawn as a chain of long and short dashes is used to indicate:

  1. dimension lines and extension lines
  2. centre lines and lines of symmetry Correct answer.
  3. hidden edges of an object
  4. visible outlines of an object

Explanation

A chain line consisting of long dashes alternating with short dashes is the standard convention for centre lines, axes of symmetry, and pitch circles. Visible outlines use continuous thick lines, and hidden edges use short dashed lines.

Question 34Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A 200 V DC shunt motor has an armature resistance of 0.5 Ω and takes an armature current of 20 A. The back emf of the motor is:

  1. 180 V
  2. 190 V Correct answer.
  3. 200 V
  4. 210 V

Explanation

For a DC motor, the supply voltage equals the back emf plus the armature voltage drop, so Eb = V − IaRa. Substituting gives Eb = 200 − (20 × 0.5) = 200 − 10 = 190 V.

Question 35Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A single-phase transformer has a core loss of 100 W and a full-load copper loss of 400 W. The load at which the efficiency is maximum is:

  1. 75% of full load
  2. 100% of full load
  3. 50% of full load Correct answer.
  4. 25% of full load

Explanation

Maximum efficiency occurs when the variable copper loss equals the constant core loss. Since copper loss varies with the square of the load fraction x, set 400x² = 100, giving x = 0.5, that is, 50% of full load.

Question 36Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In a vapour compression refrigeration cycle, the function of the expansion valve is to:

  1. separate lubricating oil from the refrigerant
  2. reduce the refrigerant pressure from condenser level to evaporator level Correct answer.
  3. remove heat from the refrigerant
  4. increase the refrigerant pressure before the compressor

Explanation

The expansion valve throttles the high-pressure liquid refrigerant from the condenser down to the low evaporator pressure, causing a drop in temperature before it enters the evaporator. The compressor raises pressure, and the condenser rejects heat.

Question 37Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A simply supported beam of span 4 m carries a central point load of 20 kN. The maximum bending moment in the beam is:

  1. 40 kN·m
  2. 10 kN·m
  3. 20 kN·m Correct answer.
  4. 80 kN·m

Explanation

For a simply supported beam with a central point load W over span L, the maximum bending moment occurs at mid-span and equals WL/4. Here M = (20 × 4)/4 = 20 kN·m.

Question 38Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The plasticity index of a soil is defined as the:

  1. ratio of the plastic limit to the liquid limit
  2. sum of the liquid limit and the plastic limit
  3. difference between the liquid limit and the plastic limit Correct answer.
  4. difference between the shrinkage limit and the plastic limit

Explanation

The plasticity index (PI) is the range of water content over which a soil remains plastic. It is calculated as the liquid limit minus the plastic limit, and a larger PI indicates a more compressible clay.

Question 39Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In a closed traverse, the sum of the interior angles of a five-sided polygon should be:

  1. 720°
  2. 360°
  3. 540° Correct answer.
  4. 180°

Explanation

The sum of the interior angles of an n-sided polygon is (n − 2) × 180°. For a five-sided traverse, (5 − 2) × 180° = 3 × 180° = 540°.

Question 40Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A 4-bit binary counter is initially reset to 0000. After 13 clock pulses, the counter output is:

  1. 1001
  2. 1011
  3. 1101 Correct answer.
  4. 1110

Explanation

A 4-bit binary counter counts modulo 16, so after 13 pulses it holds the binary value of 13. Converting 13 to binary gives 1101, since 8 + 4 + 1 = 13.

Question 41Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In metal cutting, the tool signature angle that relieves friction between the tool flank and the machined surface is the:

  1. end relief angle Correct answer.
  2. back rake angle
  3. side rake angle
  4. end cutting edge angle

Explanation

The end relief (clearance) angle is ground on the end flank of a single-point tool to provide clearance between the tool and the newly machined surface, reducing rubbing and wear. Rake angles control chip flow, and the cutting edge angle affects the direction of cutting forces.

Question 42Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A 50 Hz, 4-pole, three-phase induction motor runs at a slip of 4%. The rotor speed is:

  1. 750 rpm
  2. 1440 rpm
  3. 1500 rpm
  4. 720 rpm Correct answer.

Explanation

Synchronous speed is Ns = 120f/P = (120 × 50)/4 = 1500 rpm. Rotor speed is N = Ns(1 − s) = 1500 × 0.96 = 1440 rpm.

Question 43Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

In a first-angle projection drawing, the view placed below the front view is the:

  1. right-side view
  2. left-side view
  3. bottom view
  4. top view Correct answer.

Explanation

In first-angle projection the object is imagined between the observer and the plane of projection, so the top view is projected below the front view. Side views are placed on the opposite side from which they are viewed.

Question 44Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A 10 m wide rectangular channel carries water at a depth of 2 m with a mean velocity of 1.5 m/s. The discharge is:

  1. 30 m³/s Correct answer.
  2. 15 m³/s
  3. 3 m³/s
  4. 300 m³/s

Explanation

Discharge equals the cross-sectional area times the mean velocity. The area is 10 × 2 = 20 m², so Q = 20 × 1.5 = 30 m³/s.

Question 45Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

The main advantage of a doubly reinforced concrete beam over a singly reinforced beam of the same size is that it:

  1. eliminates the need for shear reinforcement
  2. reduces the total quantity of steel required
  3. prevents the development of any tensile stress in the concrete
  4. increases the moment of resistance when the concrete section is limited Correct answer.

Explanation

Compression steel is added in a doubly reinforced beam to supplement the concrete compression capacity when the section size is restricted by headroom or architectural limits. This raises the moment of resistance beyond the balanced singly reinforced value.

Question 46Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A 3-phase, 400 V, 50 Hz induction motor takes a line current of 20 A at a power factor of 0.8. The input power is approximately:

  1. 9.2 kW
  2. 16.0 kW
  3. 11.1 kW Correct answer.
  4. 6.4 kW

Explanation

For a balanced three-phase load, input power is P = √3 × VL × IL × cos φ. Substituting gives P = 1.732 × 400 × 20 × 0.8 ≈ 11.1 kW.

Question 47Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A 8-bit DAC has a full-scale output of 10.2 V. Its resolution is approximately:

  1. 10 mV
  2. 80 mV
  3. 20 mV
  4. 40 mV Correct answer.

Explanation

An 8-bit DAC has 2^8 − 1 = 255 steps over its full-scale range. Resolution = 10.2 V / 255 ≈ 0.04 V, or 40 mV.

Question 48Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A simply supported beam of rectangular section 100 mm wide and 200 mm deep carries a shear force of 30 kN at a section. The maximum shear stress in the section is:

  1. 3.0 N/mm²
  2. 0.75 N/mm²
  3. 1.5 N/mm²
  4. 2.25 N/mm² Correct answer.

Explanation

For a rectangular section, the maximum shear stress is 1.5 times the average shear stress. Average stress = 30 000 N / (100 × 200 mm²) = 1.5 N/mm², so maximum stress = 1.5 × 1.5 = 2.25 N/mm².

Question 49Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A 100 kVA transformer has a full-load copper loss of 1.6 kW and a core loss of 1.0 kW. The load at which the efficiency is maximum is approximately:

  1. 79% of full load Correct answer.
  2. 50% of full load
  3. 62.5% of full load
  4. 100% of full load

Explanation

Maximum efficiency occurs when the variable copper loss equals the constant core loss. If x is the load fraction, then 1.6x² = 1.0, so x² = 0.625 and x ≈ 0.79, or about 79% of full load.

Question 50Technology-specific core engineering subjects (e.g., Civil, Electrical, Mechanical, Computer)

A soil sample has a void ratio of 0.6. If the specific gravity of the soil solids is 2.70, the dry unit weight is approximately: (take γw = 9.81 kN/m³)

  1. 20.1 kN/m³
  2. 18.5 kN/m³
  3. 16.6 kN/m³ Correct answer.
  4. 14.2 kN/m³

Explanation

Dry unit weight is γd = (G·γw)/(1 + e). Substituting gives γd = (2.70 × 9.81)/(1 + 0.6) = 26.49/1.6 ≈ 16.6 kN/m³.