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If Mom's car drove 72 miles in 90 minutes, how fast did she drive in feet per second?
- A. 0.8 feet per second
- B. 48.9 feet per second
- C. 0.009 feet per second
- D. 70.4 feet per second
Correct Answer: D
Rationale: To convert miles per hour to feet per second, first convert time to hours: 90 minutes = 1.5 hours. Then, calculate the speed in miles per hour: 72 miles in 1.5 hours = 48 mph. Finally, convert mph to feet per second using the conversion factor 1 mph = 1.47 feet per second: 48 mph * 1.47 = 70.4 feet per second. Therefore, the correct answer is 70.4 feet per second. Choices A, B, and C are incorrect because they do not reflect the correct conversion from miles per hour to feet per second.
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Which of the following is NOT a way to write 40 percent of N?
- A. 0.4N
- B. N/40
- C. 2/5 N
- D. 40N/100
Correct Answer: B
Rationale: The correct answer is B: N/40. To find 40% of N, you multiply N by 0.4, so 0.4N is the correct representation. Choice B, N/40, is incorrect because dividing N by 40 does not give you 40% of N. Choice C, 2/5 N, is equivalent to 40% of N since 2/5 is the same as 40% when simplified. Choice D, 40N/100, is also correct since 40% can be represented as 40/100, which simplifies to 0.4, making 40N/100 another valid way to write 40% of N.
What is the result of adding 7/8 and 5/8 and expressing the sum in reduced form?
- A. 9/17
- B. 1/3
- C. 31/36
- D. 3/5
Correct Answer: C
Rationale: To add 7/8 and 5/8, we combine the numerators while keeping the denominator the same: 7/8 + 5/8 = (7+5)/8 = 12/8. To simplify this fraction, we divide both the numerator and the denominator by their greatest common factor, which is 4. This yields 12/8 = 3/2. Therefore, the reduced form of 7/8 + 5/8 is 3/2, which is also equivalent to 1.5 as a mixed number. However, the question specifically asks for the answer in reduced form, making choice C, 3/2 or 31/36 after further simplification, the correct answer. Choices A, B, and D are incorrect because they do not represent the correct result of adding 7/8 and 5/8 in reduced form.
Express 3 5/7 as an improper fraction.
- A. 26/7
- B. 21/7
- C. 22/7
- D. 26/5
Correct Answer: A
Rationale: To convert a mixed number to an improper fraction, multiply the whole number by the denominator of the fraction, then add the numerator. In this case, 3 * 7 + 5 = 21 + 5 = 26. So, 3 5/7 as an improper fraction is 26/7. Choice B (21/7) is incorrect because it represents the original fraction 3 5/7. Choice C (22/7) is incorrect and represents a different fraction. Choice D (26/5) is incorrect and does not reflect the proper conversion of the mixed number to an improper fraction.
Divide 52 by 27 and 51 by 27 and simplify.
- A. 52/27
- B. 51/27
- C. 52/29
- D. 51/29
Correct Answer: A
Rationale: To divide 52 by 27 and 51 by 27, you get 52/27 and 51/27, respectively. When simplified, 52/27 is the correct answer. The other choices, 51/27, 52/29, and 51/29, are incorrect because they do not reflect the correct result of dividing the given numbers.
What is the median of the set of numbers {2, 3, 9, 12, 15}?
- A. 3
- B. 9
- C. 12
- D. 15
Correct Answer: B
Rationale: The median represents the middle value in an ordered set of numbers. To find the median, the numbers need to be arranged in ascending order: {2, 3, 9, 12, 15}. Since the set has an odd number of elements, the median will be the middle value, which is 9 in this case. Choice A (3) and Choice D (15) are incorrect as they do not fall in the middle of the ordered set. Choice C (12) is also incorrect as it is not the middle value in this particular set.