Correct Answer: B

Rationale: To solve the proportion 0.1:10=x:400, first, simplify the left side to 1:100. Then, set up the proportion as 1:100=x:400. Cross multiply to get x = 4. Therefore, the correct answer is B. Choice A (5) is incorrect because it does not match the calculated value of x. Choice C (50) is incorrect as it is not the result of solving the proportion provided. Choice D (25) is incorrect as it does not align with the correct calculation of x.

Correct Answer: A

Rationale: To add fractions, you need a common denominator. In this case, the common denominator is 57 * 75 = 4275. So, (47*75 + 65*57) / 4275 = (3525 + 3705) / 4275 = 7230 / 4275. Simplifying this fraction gives 1 23/35. Choice B: 2 1/3 is incorrect as the correct result is not a mixed number. Choice C: 1 2/3 is incorrect as it does not match the simplified result of the expression. Choice D: 1 5/6 is incorrect as it is a different value from the correct result obtained by adding the fractions.

Correct Answer: B

Rationale: To find the result of dividing 3.44 by 0.6, you perform the division operation: 3.44 · 0.6 = 5.73. When rounded off to the nearest whole number, 5.73 becomes 6. Therefore, the correct answer is 6. Choice A is incorrect as the result is not 0. Choice C is incorrect as it is not the closest whole number to 5.73. Choice D is incorrect as it does not reflect the accurate division result.

Correct Answer: C

Rationale: To convert grams to milligrams, you need to multiply by 1,000 since there are 1,000 milligrams in a gram. Therefore, 7 grams is equal to 7,000 milligrams. Choice A (700 mg) is incorrect because it represents grams to milligrams incorrectly. Choice B (0.7 mg) is incorrect as it converts grams to milligrams erroneously by decimal placement. Choice D (0.07) is incorrect as it converts grams to milligrams inaccurately by misplacing the decimal point.

Correct Answer: A

Rationale: To subtract 2 5/8 from 7/8, first, convert 7/8 to an equivalent fraction with the same denominator as 2 5/8, which is 8. 7/8 equals 1 whole and 1/8. Subtracting 1 whole from 2 whole results in 1 whole, and subtracting 1/8 from 5/8 gives 4/8 or 1/2. Therefore, the answer is 1 1/2, which simplifies to 1 3/4. Choice B, 2, is incorrect as it doesn't represent the correct result of the subtraction. Choice C, 1, is incorrect as it doesn't account for the fractional part of the answer. Choice D, 2 & 1/2, is incorrect as it doesn't match the calculated result of 1 3/4.