Correct Answer: A

Rationale: To calculate the percent increase, subtract the initial value from the final value, which gives 2219 - 1432 = 787. Then, divide the increase (787) by the initial value (1432) and multiply by 100 to get the percentage: (787/1432) * 100 = 55%. Therefore, the approximate percent increase in the number of births is 55%. Choice B, 36%, is incorrect because it does not match the calculated increase. Choice C, 64%, is incorrect as it is higher than the actual percentage. Choice D, 42%, is incorrect as it is lower than the actual percentage.

Correct Answer: C

Rationale: To find 1/6 of 500, multiply 500 by 1/6: (500)(1/6) = 500/6 = 83.33. Converting the fraction to a decimal gives 83.33. Rounding this to the nearest hundredth results in 83.33. Therefore, 83.33 milliliters of blood were used for further tests. Choice A is incorrect as it does not consider the decimal value of the fraction. Choice B is incorrect as it rounds to the tenths place, not the nearest hundredth. Choice D is incorrect as it rounds up unnecessarily, as the correct answer should be rounded to 83.33.

Correct Answer: B

Rationale: The average length of a human eyelash is approximately one centimeter. A nanometer is too small to describe the length of an eyelash. A meter and a kilometer are much longer lengths and not suitable to describe the average human eyelash.

Correct Answer: A

Rationale: To calculate the percent increase, subtract the initial value from the final value, which gives 2219 - 1432 = 787. Then, divide the increase (787) by the initial value (1432) and multiply by 100 to get the percentage: (787/1432) * 100 = 55%. Therefore, the approximate percent increase in the number of births is 55%. Choice B, 36%, is incorrect because it does not match the calculated increase. Choice C, 64%, is incorrect as it is higher than the actual percentage. Choice D, 42%, is incorrect as it is lower than the actual percentage.

Correct Answer: C

Rationale: To solve this problem, we can set up a system of equations. Let the cost of one container of yogurt be y and the cost of one box of crackers be c. From the first scenario, we have 4y + 3c = 9.55. From the second scenario, we have 2y + 2c = 5.90. Solving these equations simultaneously, we find that c = $2.25. Therefore, one box of crackers costs $2.25. Choice A, $1.75, is incorrect because it does not satisfy the given conditions in the system of equations. Choice B, $2.00, is incorrect as it does not match the calculated solution. Choice D, $2.50, is incorrect as it does not align with the calculated value for one box of crackers.