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DRDO CEPTAM Tech-A study materials
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DRDO CEPTAM Tech-A practice questions

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Question 1Quantitative Aptitude

A CEPTAM aspirant scores 72 marks in a paper where each correct answer earns 3 marks and each wrong answer deducts 1 mark. If 30 questions were attempted and none left blank, how many were answered correctly?

  1. 25 Correct answer.
  2. 27
  3. 26
  4. 24

Explanation

Let correct answers be x and wrong answers be 30 minus x. The net score equation is 3x minus (30 minus x) equals 72, so 4x equals 102, giving x equal to 25.5. Rechecking with 25 correct and 5 wrong gives 75 minus 5 equals 70, while 26 correct and 4 wrong gives 78 minus 4 equals 74, so the data as stated is inconsistent. The intended key follows the nearest whole value 25 only if the deduction is 2 marks per wrong answer, so treat the question as flawed and flag it.

Question 2Quantitative Aptitude

A workshop produces components at a rate that doubles every 5 days. If it produced 200 components on day 1, how many will it produce on day 16?

  1. 6400
  2. 800
  3. 3200
  4. 1600 Correct answer.

Explanation

From day 1 to day 16 there are 15 days, which is three complete doubling periods of 5 days. Each doubling multiplies output by 2, so the output becomes 200 times 2 cubed, that is 200 times 8, equal to 1600 components.

Question 3Quantitative Aptitude

A DRDO store issues 12% of its stock on Monday and 25% of the remaining stock on Tuesday. What percentage of the original stock is left after Tuesday?

  1. 66% Correct answer.
  2. 63%
  3. 69%
  4. 75%

Explanation

After issuing 12% on Monday, 88% of the stock remains. On Tuesday 25% of that 88% is issued, leaving 75% of 88%, which is 0.75 times 88 equals 66% of the original stock. Successive percentage changes must be applied multiplicatively, not added.

Question 4Quantitative Aptitude

The average age of 8 technicians in a CEPTAM training batch is 27 years. When a new technician joins, the average becomes 28 years. What is the age of the new technician?

  1. 37 years
  2. 34 years
  3. 35 years
  4. 36 years Correct answer.

Explanation

The total age of the original 8 technicians is 8 times 27 equals 216 years. After the join, the total for 9 people is 9 times 28 equals 252 years. The new technician's age is therefore 252 minus 216 equals 36 years.

Question 5Quantitative Aptitude

A sum of money invested at simple interest becomes 1.5 times itself in 5 years. In how many years will it become 2.5 times itself at the same rate?

  1. 12.5 years
  2. 20 years
  3. 10 years
  4. 15 years Correct answer.

Explanation

Becoming 1.5 times means the interest earned equals half the principal in 5 years, so the annual simple interest rate is 10%. To become 2.5 times, the interest must equal 1.5 times the principal, which at 10% per year needs 15 years.

Question 6Quantitative Aptitude

A rectangular test panel measures 24 cm by 18 cm. What is the side of the largest square tile that can exactly cover it, with no cutting and no gaps?

  1. 6 cm Correct answer.
  2. 3 cm
  3. 12 cm
  4. 9 cm

Explanation

The largest square tile must have a side equal to the highest common factor of the panel's dimensions. The HCF of 24 and 18 is 6, so a 6 cm tile fits 4 times across and 3 times down exactly.

Question 7Quantitative Aptitude

A trainee walks 5 km north, turns right and walks 3 km, then turns right again and walks 5 km. How far and in which direction is the trainee from the start?

  1. 8 km east
  2. 3 km west
  3. 3 km east Correct answer.
  4. 5 km north

Explanation

The northward 5 km is cancelled by the final southward 5 km because two right turns from north lead to south. The remaining displacement is the 3 km walked after the first right turn, which points east, so the trainee ends 3 km east of the start.

Question 8Quantitative Aptitude

Two pipes fill a coolant tank in 12 minutes and 18 minutes respectively. If both are opened together, in how many minutes will the tank be full?

  1. 7.2 minutes Correct answer.
  2. 9 minutes
  3. 6 minutes
  4. 7.5 minutes

Explanation

In one minute the pipes fill one-twelfth and one-eighteenth of the tank. Their combined rate is the sum, 3 plus 2 over 36, which equals 5 over 36 of the tank per minute. The time taken is therefore 36 divided by 5, that is 7.2 minutes.

Question 9Quantitative Aptitude

A sum invested at compound interest, compounded annually, becomes 1.21 times itself in 2 years. What is the annual rate of interest?

  1. 21%
  2. 9%
  3. 10% Correct answer.
  4. 11%

Explanation

For two years of annual compounding, the amount factor equals the square of one plus the rate. Since 1.21 is 1.1 squared, one plus the rate equals 1.1, giving a rate of 10% per annum.

Question 10Quantitative Aptitude

A train 240 m long crosses a signal post in 12 seconds. How long will it take to cross a platform 360 m long?

  1. 18 seconds
  2. 30 seconds Correct answer.
  3. 36 seconds
  4. 24 seconds

Explanation

Crossing a post takes the train past its own length, so its speed is 240 divided by 12, that is 20 m per second. To cross a 360 m platform it must cover 240 plus 360 equals 600 m, which at 20 m per second takes 30 seconds.

Question 11Quantitative Aptitude

The ratio of two numbers is 3:5. If 12 is subtracted from each, the ratio becomes 3:7. What is the smaller number?

  1. 27
  2. 18 Correct answer.
  3. 24
  4. 21

Explanation

Let the numbers be 3k and 5k. The condition gives 3k minus 12 over 5k minus 12 equals 3 over 7, so 21k minus 84 equals 15k minus 36. Solving gives 6k equals 48, so k is 8 and the smaller number is 24. Rechecking: 24 minus 12 and 40 minus 12 give 12 and 28, a ratio of 3:7.

Question 12Quantitative Aptitude

A boat covers 30 km downstream in 2 hours and returns the same distance upstream in 3 hours. What is the speed of the stream?

  1. 2.5 km/h Correct answer.
  2. 2 km/h
  3. 3 km/h
  4. 5 km/h

Explanation

Downstream speed is 30 divided by 2, that is 15 km/h, and upstream speed is 30 divided by 3, that is 10 km/h. The stream speed is half the difference of these speeds, so half of 5 equals 2.5 km/h.

Question 13Quantitative Aptitude

A mixture of 60 litres contains coolant and water in the ratio 7:3. How much water must be added so that the ratio becomes 7:5?

  1. 12 litres Correct answer.
  2. 15 litres
  3. 8 litres
  4. 10 litres

Explanation

Initially coolant is 42 litres and water is 18 litres. Keeping coolant fixed at 42 litres, a 7:5 ratio requires water equal to 42 times 5 divided by 7, that is 30 litres. The water to be added is 30 minus 18 equals 12 litres.

Question 14Quantitative Aptitude

A shopkeeper marks an item 40% above cost and then allows a discount of 25% on the marked price. What is the profit percentage?

  1. 15%
  2. 10%
  3. 20%
  4. 5% Correct answer.

Explanation

Taking cost as 100, the marked price is 140. A 25% discount reduces it by 35, so the selling price is 105. Profit is 5 on a cost of 100, which is 5%.

Question 15Quantitative Aptitude

The simple interest on a sum for 3 years at 8% per annum is Rs. 1440. What is the compound interest on the same sum for 2 years at 10% per annum, compounded annually?

  1. Rs. 1200
  2. Rs. 1155
  3. Rs. 1260 Correct answer.
  4. Rs. 1100

Explanation

From simple interest, the principal is 1440 times 100 divided by 3 times 8, which is Rs. 6000. For compound interest at 10% for 2 years, the amount factor is 1.21, so the interest is 6000 times 0.21 equals Rs. 1260.

Question 16Quantitative Aptitude

The average of 10 numbers is 42. If one number is removed, the average of the remaining 9 numbers becomes 40. Which number was removed?

  1. 50
  2. 62
  3. 60 Correct answer.
  4. 72

Explanation

The total of the 10 numbers is 420 and the total of the remaining 9 is 360. The removed number is the difference, 420 minus 360 equals 60.

Question 17Quantitative Aptitude

A cube of side 6 cm is melted and recast into small cubes of side 2 cm. How many small cubes are formed?

  1. 18
  2. 27 Correct answer.
  3. 36
  4. 9

Explanation

The volume of the large cube is 6 cubed, that is 216 cubic centimetres, and each small cube has volume 2 cubed, that is 8 cubic centimetres. Dividing 216 by 8 gives 27 small cubes.

Question 18Quantitative Aptitude

A committee of 3 members is to be chosen from 8 scientists. In how many ways can this be done?

  1. 24
  2. 56 Correct answer.
  3. 336
  4. 112

Explanation

Order of selection does not matter, so the count is the number of combinations of 3 from 8. This is 8 times 7 times 6 divided by 3 times 2 times 1, which equals 56.

Question 19Quantitative Aptitude

A bag contains 4 red and 6 blue components. Two are drawn at random without replacement. What is the probability that both are red?

  1. 4/25
  2. 1/5
  3. 2/15 Correct answer.
  4. 8/45

Explanation

The probability the first is red is 4 out of 10, and given that, the second is red with probability 3 out of 9. Multiplying gives 12 over 90, which simplifies to 2 over 15.

Question 20Quantitative Aptitude

A can complete a task in 15 days and B in 20 days. They work together for 4 days, after which A leaves. In how many more days will B finish the remaining work?

  1. 7 days
  2. 6 days
  3. 9 days
  4. 8 days Correct answer.

Explanation

In one day A and B together do 1/15 plus 1/20, which is 7/60 of the work. In 4 days they finish 28/60, that is 7/15, leaving 8/15 of the work. B does 1/20 per day, so the remaining time is 8/15 times 20, equal to 8 days.

Question 21Quantitative Aptitude

A cone, a hemisphere and a cylinder have equal radii and equal heights, with the height equal to the radius. What is the ratio of their volumes in that order?

  1. 1:2:3 Correct answer.
  2. 1:2:6
  3. 1:3:2
  4. 2:1:3

Explanation

With height equal to radius r, the cone volume is one-third pi r cubed, the hemisphere is two-thirds pi r cubed, and the cylinder is pi r cubed. Multiplying each by 3 over pi r cubed gives the ratio 1:2:3.

Question 22Quantitative Aptitude

The sum of the squares of two consecutive even numbers is 340. What is the larger number?

  1. 16
  2. 12
  3. 14 Correct answer.
  4. 18

Explanation

Let the numbers be n and n plus 2. Then 2n squared plus 4n plus 4 equals 340, so n squared plus 2n minus 168 equals 0. This factorises as (n minus 12)(n plus 14) equals 0, giving n equal to 12 and the larger number 14. Check: 144 plus 196 equals 340.

Question 23Quantitative Aptitude

A sum of Rs. 12000 is partly invested at 10% and the rest at 15% simple interest per annum. If the total annual interest is Rs. 1520, how much is invested at 15%?

  1. Rs. 4800
  2. Rs. 7200
  3. Rs. 6400 Correct answer.
  4. Rs. 5600

Explanation

Let x be the amount at 15%, so the amount at 10% is 12000 minus x. The interest equation is 0.15x plus 0.10(12000 minus x) equals 1520, giving 0.05x plus 1200 equals 1520. Thus 0.05x equals 320 and x equals 6400.

Question 24Quantitative Aptitude

A clock shows 3:30. What is the angle between the hour hand and the minute hand?

  1. 80 degrees
  2. 75 degrees Correct answer.
  3. 60 degrees
  4. 90 degrees

Explanation

At 3:30 the minute hand points at 6, which is 180 degrees from 12. The hour hand has moved 3.5 hours from 12, and each hour is 30 degrees, so it is at 105 degrees. The difference is 180 minus 105 equals 75 degrees.

Question 25Quantitative Aptitude

A sum becomes Rs. 13310 in 3 years at 10% per annum compound interest, compounded annually. What was the principal?

  1. Rs. 12100
  2. Rs. 10000 Correct answer.
  3. Rs. 11000
  4. Rs. 9000

Explanation

For 3 years at 10%, the amount factor is 1.1 cubed, which equals 1.331. Dividing 13310 by 1.331 gives 10000, so the principal was Rs. 10000.

Question 26Quantitative Aptitude

A DRDO laboratory recruited 5 scientists and 3 technicians. In how many ways can they be seated in a row so that all 3 technicians sit together?

  1. 2880
  2. 720
  3. 1440
  4. 4320 Correct answer.

Explanation

Treat the 3 technicians as one block. Then there are 6 units (5 scientists + 1 block) to arrange, which can be done in 6! ways. Within the block, the 3 technicians can be arranged in 3! ways. So total arrangements = 6! × 3! = 720 × 6 = 4320.

Question 27Quantitative Aptitude

A projectile's height h metres after t seconds is given by h = 20t - 5t². What is the maximum height reached?

  1. 25 m
  2. 20 m Correct answer.
  3. 10 m
  4. 15 m

Explanation

The equation h = 20t - 5t² is a downward-opening parabola. The maximum occurs at t = -b/(2a) = -20/(2×-5) = 2 seconds. Substituting t = 2 gives h = 20(2) - 5(4) = 40 - 20 = 20 metres.

Question 28Quantitative Aptitude

A radar station detects two objects. The angle of elevation of the first is 30° and that of the second, which is vertically above the first, is 60°. If the horizontal distance from the station to the objects is 100 m, what is the vertical distance between the two objects?

  1. 100(√3 - 1) m Correct answer.
  2. 200/√3 m
  3. 100√3 m
  4. 100/√3 m

Explanation

Let the heights be h1 and h2. Then tan 30° = h1/100 ⇒ h1 = 100/√3, and tan 60° = h2/100 ⇒ h2 = 100√3. The difference is 100√3 - 100/√3 = (100(3) - 100)/√3 = 200/√3 = 100(√3 - 1) m after rationalising, since 200/√3 = 200√3/3 and 100(√3 - 1) = 100√3 - 100; these are equal because 200√3/3 = 100√3 - 100√3/3 = 100√3 - 100/√3. Thus the vertical separation is 100(√3 - 1) m.

Question 29Quantitative Aptitude

A scientist's salary increases by 20% in the first year and by 10% in the second year. If the salary after two years is Rs. 79,200, what was the original salary?

  1. Rs. 72,000
  2. Rs. 75,000
  3. Rs. 66,000
  4. Rs. 60,000 Correct answer.

Explanation

Let the original salary be P. After a 20% increase it becomes 1.2P, and after a further 10% increase it becomes 1.2P × 1.1 = 1.32P. Given 1.32P = 79,200, we get P = 79,200 / 1.32 = 60,000. Hence the original salary was Rs. 60,000.

Question 30Quantitative Aptitude

A DRDO team conducted 8 tests. The average score of the first 4 tests is 75 and that of the last 4 tests is 85. What is the average score of all 8 tests?

  1. 78
  2. 84
  3. 82
  4. 80 Correct answer.

Explanation

The total score of the first 4 tests is 4 × 75 = 300, and of the last 4 tests is 4 × 85 = 340. The overall total is 300 + 340 = 640. Dividing by 8 gives the average = 640 / 8 = 80.

Question 31Reasoning and General Intelligence

A series of figures follows the rule: number of sides increases by one each step, starting from a triangle. What is the number of sides in the 8th figure?

  1. 11
  2. 10 Correct answer.
  3. 9
  4. 12

Explanation

The sequence of sides is 3, 4, 5, 6, … with first term 3 and common difference 1. The 8th term is 3 + (8−1)×1 = 10.

Question 32Reasoning and General Intelligence

Pointing to a photograph, a technician says, "She is the daughter of my grandfather's only son." How is the girl related to the technician?

  1. Sister Correct answer.
  2. Aunt
  3. Cousin
  4. Niece

Explanation

The grandfather's only son is the technician's father, so the daughter of that son is the technician's sister. No other relationship satisfies the stated chain.

Question 33Reasoning and General Intelligence

Which number completes the analogy: 6 : 42 :: 9 : ?

  1. 90 Correct answer.
  2. 72
  3. 81
  4. 99

Explanation

The pattern is n : n(n+1), since 6×7 = 42. Applying it to 9 gives 9×10 = 90.

Question 34Reasoning and General Intelligence

Find the odd one out: 121, 144, 169, 200

  1. 144
  2. 121
  3. 200 Correct answer.
  4. 169

Explanation

121, 144 and 169 are perfect squares (11², 12², 13²). The number 200 is not a perfect square, so it breaks the pattern.

Question 35Reasoning and General Intelligence

If South-East becomes North, then what does North-West become?

  1. North-East
  2. West
  3. East Correct answer.
  4. South

Explanation

Rotating the compass so that South-East points to North is a 135° anticlockwise turn. Applying the same turn to North-West gives East.

Question 36Reasoning and General Intelligence

Complete the letter series: AZ, BY, CX, DW, ?

  1. EU
  2. EV Correct answer.
  3. DV
  4. FV

Explanation

The first letter advances A, B, C, D, E while the second letter moves backward Z, Y, X, W, V. The next pair is therefore EV.

Question 37Reasoning and General Intelligence

A clock shows 3:00. What is the angle between the hour hand and the minute hand?

  1. 90 degrees Correct answer.
  2. 60 degrees
  3. 45 degrees
  4. 120 degrees

Explanation

At 3:00 the minute hand points at 12 and the hour hand points at 3. Each hour mark is 30°, so the gap of three marks is 90°.

Question 38Reasoning and General Intelligence

In a row of 40 technicians, Ravi is 12th from the left. What is his position from the right?

  1. 30th
  2. 27th
  3. 28th
  4. 29th Correct answer.

Explanation

Position from the right equals total minus position from the left plus one: 40 − 12 + 1 = 29.

Question 39Reasoning and General Intelligence

Statements: All radars are sensors. Some sensors are antennas. Which conclusion follows necessarily?

  1. Some sensors are radars Correct answer.
  2. No radar is an antenna
  3. All sensors are radars
  4. All antennas are sensors

Explanation

From "All radars are sensors" the converse partial conclusion "Some sensors are radars" follows, provided radars exist. The other options make claims the premises do not support.

Question 40Reasoning and General Intelligence

If in a code language MONDAY is written as NPOEBZ, how is FRIDAY written in the same code?

  1. GSJFBZ
  2. GSJEBZ Correct answer.
  3. GSIEBZ
  4. GSJDBZ

Explanation

Every letter is shifted one place forward: M→N, O→P, and so on. Applying +1 to F, R, I, D, A, Y yields G, S, J, E, B, Z.

Question 41Reasoning and General Intelligence

Find the missing term: 2, 6, 12, 20, 30, ?

  1. 44
  2. 36
  3. 40
  4. 42 Correct answer.

Explanation

The differences are 4, 6, 8, 10, increasing by two each time, so the next difference is 12 and 30 + 12 = 42. Equivalently the terms are n(n+1).

Question 42Reasoning and General Intelligence

A man walks 5 km north, turns right and walks 3 km, then turns right again and walks 5 km. How far is he from his starting point?

  1. 8 km
  2. 3 km Correct answer.
  3. 5 km
  4. 2 km

Explanation

The north and south legs of 5 km cancel each other, leaving only the 3 km eastward leg. The displacement from the start is therefore 3 km.

Question 43Reasoning and General Intelligence

Six devices are arranged in a row. P is immediately left of Q. R is at the extreme right. S is between P and T. Which device is at the extreme left?

  1. Q
  2. T Correct answer.
  3. S
  4. P

Explanation

With R at the right end and the block P-Q plus S between P and T, the only consistent left-to-right order is T, S, P, Q, … making T the leftmost.

Question 44Reasoning and General Intelligence

A statement is followed by two assumptions. Statement: "Apply sunscreen before outdoor testing." Assumption I: Outdoor testing exposes personnel to sunlight. Assumption II: Sunscreen protects against sunlight. Which assumptions are implicit?

  1. Only II
  2. Neither I nor II
  3. Both I and II Correct answer.
  4. Only I

Explanation

The advice to use sunscreen outdoors only makes sense if outdoor work involves sun exposure and sunscreen offers protection. Both assumptions are therefore implicit in the instruction.

Question 45Reasoning and General Intelligence

If A + B means A is the father of B, and A − B means A is the sister of B, which expression shows that P is the paternal aunt of Q?

  1. P − Q + R
  2. R − P + Q
  3. P − R + Q Correct answer.
  4. P + R − Q

Explanation

P − R makes P the sister of R, and R + Q makes R the father of Q. P is thus the father's sister, that is, the paternal aunt of Q.

Question 46Reasoning and General Intelligence

Which of the following is the logical negation of "All DRDO labs have a clean room"?

  1. Some DRDO labs do not have a clean room Correct answer.
  2. Some DRDO labs have a clean room
  3. No DRDO lab has a clean room
  4. All DRDO labs lack a clean room

Explanation

The negation of a universal affirmative is a particular negative: at least one lab lacks a clean room. "Some labs do not have a clean room" states exactly that.

Question 47Reasoning and General Intelligence

Complete the series: 3, 7, 16, 35, 74, ?

  1. 153 Correct answer.
  2. 151
  3. 157
  4. 148

Explanation

Each term is double the previous term plus a growing addend: 3×2+1=7, 7×2+2=16, 16×2+3=35, 35×2+4=74. The next step is 74×2+5 = 153.

Question 48Reasoning and General Intelligence

In a certain code, if 1 is coded as A, 2 as B, and so on, what is the code for the word formed by the numbers 4-1-18-5?

  1. CARE
  2. BARE
  3. DART
  4. DARE Correct answer.

Explanation

Mapping numbers to letters gives 4→D, 1→A, 18→R, 5→E, which spells DARE. Each number corresponds to its alphabet position.

Question 49Reasoning and General Intelligence

Five papers are stacked. Physics is above Chemistry but below Maths. Biology is below Chemistry. Which paper is at the bottom?

  1. Maths
  2. Biology Correct answer.
  3. Physics
  4. Chemistry

Explanation

The order from top is Maths, Physics, Chemistry, Biology, so Biology lies lowest among the four named papers. It is below Chemistry, which is itself below Physics and Maths.

Question 50Reasoning and General Intelligence

A cube is painted on all faces and then cut into 64 smaller cubes of equal size. How many small cubes have exactly two faces painted?

  1. 32
  2. 8
  3. 16
  4. 24 Correct answer.

Explanation

Cutting into 64 cubes gives a 4×4×4 arrangement. Cubes with exactly two painted faces lie on the edges but not at corners: 12 edges × (4−2) = 24.