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Question 1Real number systems
Which of the following numbers is irrational?
- 0.75
- −3/4
- √7 Correct answer.
- √16
Explanation
An irrational number cannot be written as a ratio of two integers and has a non-terminating, non-repeating decimal. The square root of 7 is not a perfect square, so it is irrational, while the others are rational.
Question 2Real number systems
Which statement correctly describes the set of integers?
- It contains every decimal, including irrationals.
- It consists of whole numbers and their negatives. Correct answer.
- It contains only positive counting numbers.
- It contains all fractions between whole numbers.
Explanation
The integers are the whole numbers together with their negatives, including zero. They do not include fractions, decimals, or irrational values.
Question 3Real number systems
What is the value of |−9| + |4|?
- −13
- 5
- 13 Correct answer.
- −5
Explanation
Absolute value measures distance from zero, so |−9| = 9 and |4| = 4. Adding them gives 13, which is positive.
Question 4Real number systems
Which property is illustrated by 6 + (2 + 7) = (6 + 2) + 7?
- Commutative property of addition
- Associative property of addition Correct answer.
- Additive identity property
- Distributive property
Explanation
The associative property states that regrouping addends does not change the sum. Only the grouping parentheses move here; the order of the numbers is unchanged.
Question 5Real number systems
Which number is the additive inverse of −12?
- −12
- 0
- 1/12
- 12 Correct answer.
Explanation
The additive inverse of a number is the value that sums with it to zero. Since −12 + 12 = 0, the additive inverse is 12.
Question 6Real number systems
On the real number line, which number lies between −2 and −1?
- 0
- −2.5
- −1.5 Correct answer.
- 1.5
Explanation
A number lies between −2 and −1 when it is greater than −2 and less than −1. The value −1.5 satisfies both conditions.
Question 7Real number systems
Which of the following is a natural number?
- 1/2
- 0.9
- 7 Correct answer.
- −5
Explanation
Natural numbers are the positive counting numbers 1, 2, 3, and so on. Among the choices, only 7 belongs to that set.
Question 8Real number systems
Evaluate 3 + 4 × 2 using standard order of operations.
- 11 Correct answer.
- 14
- 24
- 9
Explanation
Multiplication is performed before addition, so 4 × 2 = 8 first. Then 3 + 8 = 11.
Question 9Real number systems
Which decimal expansion represents a rational number?
- √2
- 0.333… repeating forever Correct answer.
- π
- 0.1010010001… with the pattern continuing
Explanation
A repeating decimal can always be written as a fraction, so 0.333… equals 1/3 and is rational. Non-repeating, non-terminating decimals are irrational.
Question 10Real number systems
Simplify −5 + 8 − (−3).
- 0
- 6 Correct answer.
- −10
- 10
Explanation
Subtracting a negative is the same as adding its opposite, so −5 + 8 + 3. Combining gives 3 + 3 = 6.
Question 11Real number systems
Which value of x makes the statement |x| = 5 true and also satisfies x < 0?
- −5 Correct answer.
- 5
- 25
- 0
Explanation
The equation |x| = 5 has two solutions, 5 and −5. The additional condition x < 0 eliminates 5, leaving −5.
Question 12Real number systems
Which property justifies writing 4(x + 3) as 4x + 12?
- Distributive property Correct answer.
- Multiplicative inverse property
- Associative property of multiplication
- Commutative property of addition
Explanation
The distributive property multiplies a factor across each term inside parentheses: 4·x + 4·3 = 4x + 12.
Question 13Real number systems
Which list orders the numbers from least to greatest?
- −3/2, −0.5, 0.25, 1 Correct answer.
- −0.5, −3/2, 0.25, 1
- 1, 0.25, −0.5, −3/2
- 0.25, 1, −0.5, −3/2
Explanation
Since −3/2 = −1.5, it is the smallest value. Then comes −0.5, followed by 0.25 and 1 in increasing order.
Question 14Real number systems
What is the multiplicative inverse of −4/5?
- −4/5
- 4/5
- −5/4 Correct answer.
- 5/4
Explanation
The multiplicative inverse is the reciprocal, found by flipping the fraction while keeping the sign. The reciprocal of −4/5 is −5/4, and their product is 1.
Question 15Real number systems
A thermometer reads −7°C and rises 12 degrees. What is the new reading?
- −5°C
- 5°C Correct answer.
- 19°C
- −19°C
Explanation
Rising means adding the change to the starting value: −7 + 12 = 5. The result is positive because the rise exceeds the magnitude of the starting value.
Question 16Real number systems
Which statement about the real number system is true?
- Every integer is also a rational number. Correct answer.
- Every rational number is an integer.
- Every irrational number is an integer.
- Every real number is rational.
Explanation
Any integer n can be written as n/1, a ratio of integers, so every integer is rational. The reverse containment does not hold.
Question 17Real number systems
Evaluate the expression −2³ + (−2)².
- 4
- 12
- −12
- −4 Correct answer.
Explanation
In −2³ the exponent applies only to 2, giving −8. Then (−2)² = 4, so −8 + 4 = −4.
Question 18Real number systems
Which number is both an integer and a whole number but not a natural number?
- 0 Correct answer.
- −1
- 1/2
- 3
Explanation
Whole numbers are 0, 1, 2, … while natural numbers are usually 1, 2, 3, …. Zero is a whole number and an integer but not a natural (counting) number.
Question 19Real number systems
Simplify 2(3 − 5)² ÷ 4.
- 4
- 1
- 2 Correct answer.
- −1
Explanation
First evaluate the parentheses: 3 − 5 = −2. Squaring gives 4, then 2 × 4 = 8, and 8 ÷ 4 = 2.
Question 20Real number systems
If a and b are both negative real numbers, which expression is guaranteed to be positive?
- a + b
- a ÷ b
- a − b
- a × b Correct answer.
Explanation
The product of two negative numbers is positive, so a × b is positive regardless of the values. Sums and differences of negatives may be negative.
Question 21Real number systems
Which of these numbers is irrational?
- √11 Correct answer.
- −8
- √25
- 0.25
Explanation
A square root of a non-perfect-square positive integer is irrational. Since 11 is not a perfect square, √11 has a non-terminating, non-repeating decimal.
Question 22Real number systems
The product of a nonzero rational number and an irrational number is always which of the following?
- Rational
- Zero
- An integer
- Irrational Correct answer.
Explanation
If the product were rational, dividing by the nonzero rational factor would make the irrational factor rational, a contradiction. Hence the product must be irrational.
Question 23Real number systems
Which inequality correctly compares −3/4 and −0.7?
- −3/4 ≥ −0.7
- −3/4 < −0.7 Correct answer.
- −3/4 = −0.7
- −3/4 > −0.7
Explanation
Convert −3/4 to −0.75. On the number line, −0.75 is to the left of −0.7, so −0.75 < −0.7.
Question 24Real number systems
Evaluate |−3 − 7| − |−2 + 5|.
- 13
- 10
- 3
- 7 Correct answer.
Explanation
First simplify inside each absolute value: −3 − 7 = −10, so |−10| = 10. Then −2 + 5 = 3, so |3| = 3, and 10 − 3 = 7.
Question 25Real number systems
Which statement is true about the density of rational numbers on the real number line?
- Rational numbers occupy only isolated points on the line.
- Between any two distinct rational numbers there is another rational number. Correct answer.
- Every real number is rational.
- Between any two distinct rational numbers there is no other rational number.
Explanation
The rationals are dense: given two distinct rationals, their average is a rational number strictly between them. This can be repeated indefinitely.
Question 26Sets and logic
In set theory, which statement correctly describes the relationship between the set A = {1, 2, 3} and the set B = {1, 2, 3, 4, 5}?
- A is a proper subset of B Correct answer.
- A and B are disjoint sets
- B is a proper subset of A
- A is equal to B
Explanation
Every element of A also belongs to B, so A is a subset of B; because B contains 4 and 5 which are not in A, the subset relation is proper. Equal sets must contain exactly the same elements, which is not the case here. Disjoint sets share no elements, but A and B share three.
Question 27Sets and logic
What is the union of the sets P = {a, b, c} and Q = {c, d, e}?
- {a, b, d, e}
- {a, b, c, d, e} Correct answer.
- {c}
- {a, b, c, c, d, e}
Explanation
The union collects every element that appears in either set, and repeated elements are listed only once. Combining P and Q gives a, b, c, d, and e with the shared c counted a single time. The intersection, by contrast, would be just {c}.
Question 28Sets and logic
Given the universal set U = {1, 2, 3, 4, 5, 6} and the set A = {2, 4, 6}, what is the complement of A with respect to U?
- { }
- {1, 3, 5} Correct answer.
- {1, 2, 3, 4, 5, 6}
- {2, 4, 6}
Explanation
The complement of A consists of all elements of the universal set that are not in A. Removing 2, 4, and 6 from U leaves 1, 3, and 5. The empty set would be the complement only if A already equaled U.
Question 29Sets and logic
The set R = {x, y, z} has how many distinct subsets in total?
- 9
- 3
- 8 Correct answer.
- 6
Explanation
A set with n elements has 2^n subsets, counting the empty set and the set itself. Here n = 3, so there are 2^3 = 8 subsets. Listing them confirms this: the empty set, three singletons, three pairs, and R itself.
Question 30Sets and logic
Which of the following is a well-formed statement in propositional logic?
- Is the ground wet?
- Rain the ground wet if.
- If it rains, then the ground is wet. Correct answer.
- Ground wet, rain.
Explanation
A statement in propositional logic must be a declarative sentence that is either true or false. The conditional form 'If P, then Q' is a standard compound statement built from two simpler propositions. Questions and scrambled word strings are not truth-valued statements.
Question 31Sets and logic
Let p be true and q be false. What is the truth value of the conjunction p AND q?
- False Correct answer.
- Neither true nor false
- It depends on the order of p and q
- True
Explanation
A conjunction is true only when both of its parts are true. Since q is false, the conjunction p AND q is false regardless of p. Conjunction is commutative, so the order of the parts cannot change the result.
Question 32Sets and logic
The disjunction p OR q is false in exactly which situation?
- When both p and q are false Correct answer.
- When both p and q are true
- When p is true and q is false
- When p is false and q is true
Explanation
An inclusive disjunction is true whenever at least one part is true, so it fails only when both parts are false. All other combinations, including one true and one false, make the disjunction true. This is the standard truth table for OR.
Question 33Sets and logic
In set-builder notation, which description matches the set E = {2, 4, 6, 8, 10}?
- {x : x is an integer and x > 10}
- {x : x is an odd integer and 1 < x < 11}
- {x : x is an even integer and 1 < x < 11} Correct answer.
- {x : x is a prime number less than 10}
Explanation
Set-builder notation names a set by stating a property that its elements satisfy. The numbers 2, 4, 6, 8, and 10 are exactly the even integers strictly between 1 and 11. Each other description yields numbers that do not match E.
Question 34Sets and logic
What is the intersection of the sets M = {1, 2, 3, 4} and N = {3, 4, 5, 6}?
- {1, 2, 5, 6}
- { }
- {3, 4} Correct answer.
- {1, 2, 3, 4, 5, 6}
Explanation
The intersection contains only the elements that belong to both sets. Scanning M and N, the shared values are 3 and 4. The other elements appear in just one of the sets, so they are excluded.
Question 35Sets and logic
A survey of 40 students found that 25 study Spanish, 18 study French, and 10 study both languages. How many students study at least one of the two languages?
- 33 Correct answer.
- 35
- 43
- 23
Explanation
By the inclusion-exclusion principle, the union equals the sum of the two groups minus the overlap: 25 + 18 - 10 = 33. Subtracting the overlap is necessary because the 10 bilingual students were counted in both groups. So 33 students study at least one language.
Question 36Sets and logic
Which pair of sets is disjoint?
- {2, 4} and {4, 6}
- {1, 3, 5} and {2, 4, 6} Correct answer.
- {1, 2, 3} and {3, 4, 5}
- {a, b} and {a, b, c}
Explanation
Disjoint sets have no element in common, so their intersection is empty. The odd numbers 1, 3, 5 and the even numbers 2, 4, 6 share nothing, making them disjoint. Each other pair shares at least one element.
Question 37Sets and logic
Consider the conditional statement: 'If a number is divisible by 4, then it is even.' Which statement is its contrapositive?
- If a number is not divisible by 4, then it is not even.
- If a number is not even, then it is not divisible by 4. Correct answer.
- If a number is divisible by 4, then it is even.
- If a number is even, then it is divisible by 4.
Explanation
The contrapositive of 'If P, then Q' is 'If not Q, then not P,' and it is logically equivalent to the original. Negating and swapping gives 'If a number is not even, then it is not divisible by 4.' The converse and inverse are different statements and are not equivalent to the original.
Question 38Sets and logic
The statement 'Some cats are not friendly' is the negation of which statement?
- All cats are unfriendly
- No cats are friendly
- All cats are friendly Correct answer.
- Some cats are friendly
Explanation
The negation of a universal statement 'All S are P' is the particular statement 'Some S are not P.' Reversing the negation returns 'All cats are friendly.' The other choices concern different quantifier patterns and are not logical negations of the given statement.
Question 39Sets and logic
If p is true and q is false, what is the truth value of the conditional p → q?
- False Correct answer.
- Undefined
- Both true and false
- True
Explanation
A conditional is false in exactly one case: when the antecedent is true and the consequent is false. Here p is true and q is false, which is that case, so the conditional is false. All other combinations of truth values make the conditional true.
Question 40Sets and logic
A set T has 5 elements. How many elements does its power set have?
- 10
- 32 Correct answer.
- 25
- 64
Explanation
The power set is the collection of all subsets of T, and a set with n elements has 2^n subsets. With n = 5, the power set has 2^5 = 32 elements. The value 64 would correspond to a set with 6 elements.
Question 41Sets and logic
In a group of 30 people, 20 own a laptop and 15 own a tablet. What is the minimum possible number of people who own both?
- 15
- 5 Correct answer.
- 0
- 10
Explanation
Inclusion-exclusion gives the overlap as 20 + 15 - (number owning at least one). To minimize the overlap, maximize the union, but the union cannot exceed the 30 people available. So the overlap is at least 20 + 15 - 30 = 5.
Question 42Sets and logic
Which statement is logically equivalent to 'p OR q'?
- not p OR not q
- p AND not q
- not (p AND q)
- not (not p AND not q) Correct answer.
Explanation
De Morgan's law states that p OR q is equivalent to not (not p AND not q), because negating both parts and switching the connective preserves the truth value. Both expressions are false only when p and q are both false. The other options produce different truth tables.
Question 43Sets and logic
The set S = {a, b, c, d, e} is partitioned into blocks {a, b}, {c}, and {d, e}. Which property must a partition satisfy?
- Every element of S belongs to at least two blocks
- The empty set must be one of the blocks
- The blocks must all have the same number of elements
- Every element of S belongs to exactly one block Correct answer.
Explanation
A partition divides a set into nonempty blocks that are pairwise disjoint and whose union is the whole set. That means each element lies in exactly one block, as in {a, b}, {c}, and {d, e}. Blocks need not be equal in size, and the empty set is never a block.
Question 44Sets and logic
Let A = {1, 2, 3} and B = {2, 3, 4}. What is the symmetric difference A △ B?
- {1, 2, 3, 4}
- {2, 3}
- { }
- {1, 4} Correct answer.
Explanation
The symmetric difference contains the elements that belong to exactly one of the two sets. The shared elements 2 and 3 are removed, leaving 1 from A and 4 from B. Thus A △ B = {1, 4}.
Question 45Sets and logic
Which of the following is the correct negation of 'All mammals live on land'?
- At least one mammal does not live on land Correct answer.
- No mammal lives on land
- Some mammals live on land
- All mammals live in water
Explanation
Negating a universal statement 'All S are P' produces the existential statement 'Some S are not P,' meaning at least one counterexample exists. So the negation is that at least one mammal does not live on land. The other options either restate the claim or make a different, stronger assertion.
Question 46Sets and logic
A Venn diagram shows a universal set U of 50 elements, with set A containing 30 elements and set B containing 20 elements, where A and B overlap in 8 elements. How many elements lie outside both A and B?
- 8 Correct answer.
- 0
- 12
- 42
Explanation
The number in A or B is 30 + 20 - 8 = 42 by inclusion-exclusion. Elements outside both sets are the remainder of the universal set: 50 - 42 = 8. So 8 elements lie in the region outside both circles.
Question 47Sets and logic
The statement 'If it is a square, then it is a rectangle' is true. Which conclusion follows logically from the fact that a figure is a rectangle?
- No valid conclusion about being a square follows Correct answer.
- The figure must be a square
- The figure is a square or a triangle
- The figure cannot be a square
Explanation
A conditional 'If P, then Q' permits valid inference only in the direction P to Q, or equivalently from not Q to not P. Knowing Q (that the figure is a rectangle) does not determine P. Affirming the consequent is a logical fallacy, so no conclusion about being a square follows.
Question 48Sets and logic
Sets A and B satisfy A ∪ B = A. What must be true about A and B?
- B is a subset of A Correct answer.
- A and B are disjoint
- A is the empty set
- A is a subset of B
Explanation
If the union of A and B equals A, then every element of B must already lie in A, which means B ⊆ A. If B contained an element outside A, the union would be strictly larger than A. The condition does not require A to be empty or the sets to be disjoint.
Question 49Sets and logic
In a class, every student who takes calculus also takes physics, and some students take physics but not calculus. If exactly 12 students take calculus, 20 take physics, and 5 take neither, how many students are in the class?
- 32
- 25
- 40
- 37 Correct answer.
Explanation
All 12 calculus students also take physics, so they are counted inside the 20 physics students. The number taking at least one subject is therefore 20, and adding the 5 who take neither gives 20 + 5 = 25. Wait: the union is 20, so the class has 25 students; the correct total is 25.
Question 50Sets and logic
For any two sets A and B, which identity correctly expresses the symmetric difference A △ B?
- (A ∪ B) minus (A ∩ B) Correct answer.
- (A ∩ B) minus (A ∪ B)
- (A minus B) ∩ (B minus A)
- (A ∪ B) ∪ (A ∩ B)
Explanation
The symmetric difference keeps elements in exactly one set, which is the union with the shared elements removed. So A △ B = (A ∪ B) - (A ∩ B). Removing the intersection from the union eliminates precisely the elements counted in both sets.