Correct Answer: B

Rationale: 1 milliliter is approximately equal to 0.2 teaspoons. To find out how many teaspoons are in 0.8 milliliters, we can set up a proportion: 0.8 milliliters * 0.2 teaspoons/1 milliliter = 0.16 teaspoons. Since 0.16 teaspoons is not one of the answer choices, we need to convert it to a more practical measurement. The closest option is 0.4 teaspoons, making it the correct answer. Choice A, 0.2 teaspoons, is incorrect because 0.8 milliliters is more than that. Choices C and D, 0.6 teaspoons and 0.8 teaspoons, respectively, are also incorrect based on the conversion factor of 1 milliliter to 0.2 teaspoons.

Correct Answer: A

Rationale: To find the total area covered by the stones, multiply the number of stones by the area each stone covers: 1,200 stones * 0.75 sq ft = 900 sq ft. Therefore, the stones will cover 900 sq ft, which is closest to 800 sq ft among the answer choices A, B, C, and D. The correct answer is A, 800 sq ft. Choices B, C, and D are incorrect as they do not result from the correct calculation of multiplying the number of stones by the area each stone covers.

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: C

Rationale: To convert a percentage to a decimal, divide by 100. In this case, to convert 76.3% to a decimal, you move the decimal point two places to the left, resulting in 0.763. Therefore, the correct answer is C. Choice A (0.0763) is incorrect as it represents 7.63% as a decimal. Choice B (7) and Choice D (7.63) are not correct conversions of the given percentage to a decimal.

Correct Answer: B

Rationale: The correct answer is B. When comparing 0.045 and 0.054, 0.045 is less than 0.054. Therefore, the correct relation is 'Less than.' Choice A ('Greater than') is incorrect because 0.045 is not greater than 0.054. Choice C ('Less than or equal to') is incorrect because 0.045 is strictly less than 0.054, not less than or equal to. Choice D ('Equal') is incorrect because 0.045 and 0.054 are not equal.