If 30% of a given number is 18, what is the full number?

Correct Answer: A

Rationale: If 30% of a number is 18, you can find the full number by dividing 18 by 0.30 (the decimal equivalent of 30%). This calculation results in 60. Therefore, the full number is 60. Choice B (30) is the result if 30% of the number itself was calculated, not the full number. Choices C (40) and D (45) are incorrect and do not align with the given information.

Correct Answer: B

Rationale: To find 20% of 150, you need to multiply 150 by 0.20: 150 0.20 = 30. Therefore, 20% of 150 is indeed 30. Choice A (25) is incorrect as it represents 20% of 125, not 150. Choice C (35) is incorrect as it represents more than 20% of 150. Choice D (20) is incorrect as it is the original percentage to find.

Correct Answer: C

Rationale: To calculate the number of mils, first, convert 1.5 grams to milligrams (1.5 grams = 1500 mg). Then, since 1 mil contains 500 mg, divide 1500 mg by 500 mg/mil, resulting in 3 mils required to contain 1.5 grams of substance. Choice A, 9, is incorrect because it miscalculates the conversion. Choice B, 2, is incorrect as it does not consider the correct conversion factor. Choice D, 5, is incorrect as it also miscalculates the conversion.

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.

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.

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.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: A

Rationale: To convert 2 quarts to liters, we can use the conversion factor that 1 quart is approximately equal to 0.95 liters. Therefore, 2 quarts would be approximately 1.9 liters, which is closest to 2 liters. As the measuring device is marked in liters, the teacher's aide should use 2 liters of water to dilute the contents of the package. Choice A is correct. Choice B is incorrect because it's the same as the original amount in quarts. Choice C is incorrect as it suggests using more water than necessary. Choice D is incorrect as it suggests using significantly more water than necessary.

Correct Answer: A

Rationale: 1/2 oz of perfume is equal to approximately 15 mL. To convert ounces to milliliters, we need to know that 1 oz is approximately 30 mL. Therefore, half an ounce, which is 1/2 oz, would be half of 30 mL, which equals 15 mL. Choice B, 20 mL, is incorrect as it does not correspond to the conversion factor of 1 oz to 30 mL. Choice C, 10 mL, is incorrect as it is half of the actual value. Choice D, 50 mL, is incorrect as it is the value of 1 oz rather than half an ounce.