Solve: 2 - 8(24 · 2).
- A. -94
- B. -92
- C. -96
- D. -90
Correct Answer: A
Rationale: To solve the expression, we follow the order of operations (PEMDAS). First, we divide 24 by 2 to get 12. Then, we multiply 8 by 12, which equals 96. Finally, we subtract 96 from 2: 2 - 96 = -94. Therefore, the correct answer is A, '-94'. Choices B, C, and D are incorrect as they do not follow the correct order of operations or make errors during calculation.
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X/4 = 9/x, solve for x.
- A. x = 6
- B. x = 3
- C. x = 9
- D. x = 2
Correct Answer: A
Rationale: To solve X/4 = 9/x, cross multiply to get x^2 = 36. Taking the square root of both sides gives x = 6. Choice A is correct because x = 6 satisfies the equation x^2 = 36. Choices B, C, and D are incorrect as they do not satisfy the equation when substituted back into it.
A vitamin's expiration date has passed. It was supposed to contain 500 mg of calcium, but it has lost 325 mg of calcium. How many mg of calcium are left?
- A. 175 mg
- B. 135 mg
- C. 185 mg
- D. 200 mg
Correct Answer: A
Rationale: The correct answer is A: 175 mg. The vitamin originally contained 500 mg of calcium. After losing 325 mg, the remaining amount of calcium is calculated as 500 mg - 325 mg = 175 mg. Choice B (135 mg) is incorrect because the vitamin lost more calcium than that. Choices C (185 mg) and D (200 mg) are incorrect as they do not consider the amount of calcium lost from the original 500 mg.
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.
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.
Erin has 6.25 peach pies. She gives Rose 3.75 of the peach pies. How many pies does Erin have left?
- A. 2 peach pies
- B. 3 peach pies
- C. 1 peach pie
- D. 2 peach pies
Correct Answer: A
Rationale: To find how many pies Erin has left, subtract 3.75 from 6.25: 6.25 - 3.75 = 2.5 peach pies. Erin has 2.5 peach pies left, which rounds down to 2 pies, making choice A the correct answer. Choices B, C, and D are incorrect because they do not reflect the correct subtraction result.