Convert to metric: 7 grams = x milligrams

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: 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: D

Rationale: To find the value of x, cross multiply in the ratio 18:x=10:300. This gives 18 * 300 = 10 * x. Solving for x, x = 540. Therefore, the correct answer is D. Choice A (16), Choice B (180), and Choice C (30) are incorrect because they do not satisfy the proportion equation 18:x=10:300 when cross multiplied.

Correct Answer: D

Rationale: To divide mixed numbers, convert them to improper fractions. 5 & 3/4 = 23/4 and 1/2 = 2/1. So, 23/4 · 2/1 = 23/4 * 1/2 = 23/8 = 2 & 7/8. Therefore, 5 & 3/4 divided by 1/2 reduces to 11 & 1/2. Choices A, B, and C are incorrect because they do not represent the correct result of dividing 5 & 3/4 by 1/2.

Correct Answer: D

Rationale: To find the value of x in the given ratio and proportion, we can set up the equation as 15:2000=x:200. Cross multiply to get x * 2000 = 15 * 200. Simplifying this gives x = 1. Therefore, the correct answer is D, which is 1. Choice A (7), Choice B (0), and Choice C (7,777) are incorrect as they do not match the correct calculation of x.