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What is (12/15) · (3/5) = ?
- A. 1 1/3
- B. 1 2/3
- C. 2 1/3
- D. 1
Correct Answer: A
Rationale: To divide fractions, you multiply by the reciprocal of the divisor. (12/15) · (3/5) is the same as (12/15) * (5/3). Cancel out common factors to simplify: 12 · 3 = 4, 15 · 5 = 3. So, the expression simplifies to 4/3, which is 1 1/3 in mixed number form. Choice A, 1 1/3, is the correct answer. Choices B, C, and D are incorrect because they do not represent the simplified form of the division of the given fractions.
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The height of a building is 150 feet. If each floor of the building is 12 feet high, how many floors are in the building?
- A. 13 floors
- B. 15 floors
- C. 10 floors
- D. 18 floors
Correct Answer: A
Rationale: To determine the number of floors in the building, divide the total height of the building (150 feet) by the height of each floor (12 feet). 150 feet · 12 feet per floor = 12.5 floors. Since floors cannot be in fractions, the answer is rounded down to the nearest whole number, which is 13 floors. Therefore, the correct answer is A: 13 floors. Choice B (15 floors) is incorrect because the calculation results in 12.5 floors, which should be rounded down. Choices C (10 floors) and D (18 floors) are incorrect as they do not accurately reflect the division result and rounding down process.
In a class of 25 students, 44% are boys. How many boys are there?
- A. 10 boys
- B. 11 boys
- C. 9 boys
- D. 13 boys
Correct Answer: B
Rationale: To find the number of boys in the class, calculate 44% of 25 students. 44% of 25 is calculated as follows: 0.44 x 25 = 11 boys. Therefore, there are 11 boys in the class. Choice A, 10 boys, is incorrect as it miscalculates the percentage. Choice C, 9 boys, is incorrect as it is less than 11. Choice D, 13 boys, is incorrect as it is greater than the correct calculation.
Given 15:x=3:8, find x.
- A. x=40
- B. x=20
- C. x=30
- D. x=10
Correct Answer: A
Rationale: To find x, we set up the proportion 15:x = 3:8. Cross multiply to get 15*8 = 3*x, which simplifies to 120 = 3x. Dividing by 3 on both sides gives x = 40. Therefore, x=40 is the correct answer. Choices B, C, and D are incorrect because they do not match the correct calculation. Option B results from incorrectly dividing 15 by 3 instead of multiplying it by 8. Option C comes from dividing 15 by 3, and Option D is the result of dividing 15 by 8 instead of multiplying by 3.
What is the result of adding 5 2/9 and 1 2/9?
- A. 6 4/9
- B. 7 5/9
- C. 7
- D. 5 2/9
Correct Answer: A
Rationale: To add mixed numbers with fractions, first add the whole numbers together: 5 + 1 = 6. Then add the fractions: 2/9 + 2/9 = 4/9. Combining the whole number and the fraction parts gives 6 4/9. Therefore, the correct answer is 6 4/9. Choice B (7 5/9) is incorrect as the fractions were not added correctly. Choice C (7) is incorrect as it does not account for the fractions. Choice D (5 2/9) is one of the original numbers and not the sum of both.
7 is divisible by which of the following numbers?
- A. 2 only
- B. 3 only
- C. 1 and 7 only
- D. 2, 3, and 7
Correct Answer: D
Rationale: Rationale:
1. 7 is divisible by 1 because every number is divisible by 1.
2. 7 is divisible by 7 because any number is divisible by itself.
3. 7 is not divisible by 2 because 7 is an odd number and not divisible by 2.
4. 7 is not divisible by 3 because the sum of the digits of 7 (7) is not divisible by 3.
Therefore, 7 is divisible by 1, 7, and itself (7), making the correct answer D) 2, 3, and 7.