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What is the result of the expression 4/5 + 6/7?
- A. 1 23/35
- B. 2 5/7
- C. 1 1/7
- D. 1 3/4
Correct Answer: A
Rationale: To add fractions with different denominators, you first need to find a common denominator. In this case, the common denominator for 5 and 7 is 35. Then, convert each fraction to have a denominator of 35. 4/5 becomes 28/35, and 6/7 becomes 30/35. Adding these fractions together gives 58/35, which simplifies to 1 23/35. Therefore, the correct answer is A, 1 23/35. Choice B, 2 5/7, is incorrect because it does not match the correct result. Choice C, 1 1/7, is incorrect as it is not the simplified form of the sum of the fractions. Choice D, 1 3/4, is incorrect as it is a different result and not the sum of 4/5 and 6/7.
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A roast was cooked at 325°F in the oven for 4 hours. The internal temperature rose from 32°F to 145°F. What was the average rise in temperature per hour?
- A. 20
- B. 32
- C. 28
- D. 37°F/hr
Correct Answer: C
Rationale: The temperature increased from 32°F to 145°F, resulting in a total increase of 145°F - 32°F = 113°F. Dividing this total increase by the 4 hours of cooking time gives an average rise of 113°F · 4 = 28.25°F per hour, which can be rounded to 28°F per hour. Therefore, the correct answer is 28. Choice A (20) is incorrect because it does not reflect the actual average rise in temperature per hour. Choice B (32) is incorrect as it does not consider the total temperature increase and divide it by the total hours. Choice D (37°F/hr) is incorrect as it does not match the calculated average rise in temperature per hour.
30 1/2 - 13 3/4 = ?
- A. 16 3/4
- B. 17
- C. 15 1/4
- D. 15
Correct Answer: A
Rationale: To solve the expression 30 1/2 - 13 3/4, first convert the mixed numbers to improper fractions. 30 1/2 is equivalent to 61/2 and 13 3/4 is equivalent to 55/4. Subtracting 55/4 from 61/2 gives 16 3/4, which is the correct answer. Choice B (17) is incorrect as the correct answer is a mixed number, not a whole number. Choice C (15 1/4) is incorrect as it doesn't result from subtracting the given fractions. Choice D (15) is incorrect; the correct answer is greater than 15.
How many liters are in 300 milliliters?
- A. 0.03 liters
- B. 3 liters
- C. 0.3 liters
- D. 0.003 liters
Correct Answer: C
Rationale: To convert milliliters to liters, you need to divide by 1000 since there are 1000 milliliters in 1 liter. Therefore, 300 milliliters · 1000 = 0.3 liters. Choice A, 0.03 liters, is the result of dividing by 10 instead of 1000. Choice B, 3 liters, is the result of multiplying instead of dividing. Choice D, 0.003 liters, is the result of dividing by 1000 twice, which is incorrect.
7:5=91:x. Find x.
- A. x=65
- B. x=55
- C. x=75
- D. x=85
Correct Answer: A
Rationale: To solve the proportion 7:5=91:x, cross multiply to get 7x = 5 * 91. Then, solve for x by dividing both sides by 7, which gives x = 65. Therefore, the correct answer is x=65. Choice B, x=55, is incorrect because it does not satisfy the proportion equation. Choices C and D, x=75 and x=85, are also incorrect as they do not match the calculated value of x when the proportion is solved.
Find x. 120:x = 40:0.5.
- A. 60
- C. 1
- D. 25
Correct Answer: C
Rationale: To find x, set up the proportion and solve for x: 120/x = 40/0.5. Cross multiply to get 120 * 0.5 = 40x. This simplifies to 60 = 40x. Divide by 40 to isolate x, giving x = 60/40 = 1. Therefore, the correct answer is C, which is 1. Choice A (60) is incorrect because it does not match the correct calculation. Choice B (0) is incorrect as the calculation results in x = 1, not 0. Choice D (25) is incorrect as it does not match the correct calculation of x = 1.