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81:X::9:27. Find X.
- A. 3
- B. 27
- C. 21
- D. 9
Correct Answer: B
Rationale: To find X in the given proportion 81:X::9:27, you can set up the equation 81/X = 9/27. Cross-multiplying gives 81 * 27 = 9 * X, which simplifies to 2187 = 9X. Dividing both sides by 9 results in X = 27. Therefore, the correct answer is B. Choice A (3) is incorrect as it does not satisfy the proportion. Choice C (21) is incorrect as it is not the correct value to make the proportion valid. Choice D (9) is incorrect as it does not align with the proportion provided.
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When a die is rolled, what is the probability of rolling an odd number?
- A. 16.67%
- B. 33.33%
- C. 75%
- D. 50%
Correct Answer: D
Rationale: When a die is rolled, there are 3 odd numbers (1, 3, 5) out of a total of 6 possible outcomes. The probability of rolling an odd number is calculated by dividing the number of favorable outcomes (3) by the total number of outcomes (6), resulting in a probability of 3/6 or 50%. Therefore, the correct answer is D. Choices A, B, and C are incorrect because they do not reflect the correct probability calculation for rolling an odd number on a standard six-sided die.
What percentage of 40 is 8?
- A. 20%
- B. 15%
- C. 10%
- D. 25%
Correct Answer: C
Rationale: To find the percentage of 8 in 40, divide 8 by 40 to get 0.2. Multiply this result by 100 to convert it to a percentage: 0.2 100 = 10%. Therefore, 8 is 10% of 40, making choice C the correct answer. Choices A, B, and D are incorrect percentages calculated from incorrect divisions and multiplications.
At a comic book store, Robert purchased three comics for $2.65 each. If he paid with a $20 bill, how much change did he receive?
- A. $12.05
- B. $11.05
- C. $10.00
- D. $13.50
Correct Answer: A
Rationale: Robert spent a total of $7.95 on three comics ($2.65 each). When he paid with a $20 bill, the change he received can be calculated by subtracting the total cost from the payment amount: $20 - $7.95 = $12.05. Therefore, Robert received $12.05 in change. Choice B ($11.05) is incorrect because it doesn't reflect the correct calculation. Choice C ($10.00) is incorrect as it doesn't consider the total cost of the comics. Choice D ($13.50) is incorrect as it overestimates the change Robert received.
An IV drip delivers medication at a rate of 40 drops per minute. Each drop contains 0.05 milliliters of the medication. How many milliliters of medication are delivered in one hour?
- A. 12 milliliters
- B. 24 milliliters
- C. 60 milliliters
- D. 120 milliliters
Correct Answer: D
Rationale: To find the amount of medication delivered in one hour, we first calculate the amount delivered in one minute by multiplying the number of drops per minute (40) by the volume of each drop (0.05 milliliters). This gives us 2 milliliters per minute. Then, to find the total amount delivered in one hour, we multiply 2 milliliters per minute by the number of minutes in an hour (60), resulting in 120 milliliters. Therefore, the correct answer is 120 milliliters. Choices A, B, and C are incorrect as they do not correctly calculate the total volume of medication delivered in one hour.
What percentage of her income is left after Mary spent 15%?
- A. 12%
- B. 85%
- C. 75%
- D. 95%
Correct Answer: B
Rationale: To determine the percentage of income remaining after spending 15%, subtract the percentage spent from 100% (100% - 15% = 85%). Therefore, Mary has 85% of her income left, which aligns with answer choice B. Choice A (12%) is incorrect because it represents the remaining amount after spending 88% of her income. Choice C (75%) is incorrect as it does not account for the 15% already spent. Choice D (95%) is incorrect as it does not consider the amount spent by Mary.