Correct Answer: D

Rationale: A perfect square is a number obtained by squaring an integer. In this case, 16 is a perfect square because it is the result of squaring 4 (4 x 4 = 16). The other answer choices, 10, 12, and 15, are not the product of squaring any whole number, making them incorrect. Therefore, the correct answer is 16, as it is a perfect square.

Correct Answer: B

Rationale: To calculate the percentage of her earnings that Jill saved, divide the amount saved ($140) by the total earnings ($400) and then multiply by 100 to find the percentage. Therefore, (140/400) * 100 = 35%. Jill saved 35% of her earnings. Choice A (30%) is incorrect because it underestimates the percentage saved. Choice C (40%) is incorrect as it overestimates the percentage saved. Choice D (25%) is incorrect for the same reason. The correct calculation is 140/400 = 0.35 * 100 = 35%.

Correct Answer: A

Rationale: To convert meters to millimeters, you multiply by 1000 since there are 1000 millimeters in 1 meter. Therefore, 5 meters multiplied by 1000 equals 5000 millimeters. Choice A is correct as it represents the accurate conversion from meters to millimeters. Choices B, C, and D are incorrect as they do not provide the correct conversion factor from meters to millimeters.

Correct Answer: A

Rationale: To convert pounds to grams, multiply the weight in pounds by the conversion factor of 453.59 grams per pound. Therefore, 7 pounds x 453.59 grams/pound = 3175.13 grams, which is the weight of a 7 lb. baby in grams. Choice A is correct. Choice B (4000 grams) is incorrect as it does not use the correct conversion factor. Choice C (4535 grams) is incorrect as it seems to have used a rounding error. Choice D (3500 grams) is incorrect as it does not apply the correct conversion factor.

Correct Answer: B

Rationale: To find the total staff working that day, add up all the staff members: 25 registered nurses + 75 unlicensed assistants + 5 phlebotomists + 6 receptionists + 45 physicians = 156 staff members. Since the staff was at 68% strength, multiply 156 by 0.68 to get 106. Therefore, approximately 106 people were working that day. Choice A, 102, is incorrect because it underestimates the total staff. Choice C, 98, is incorrect because it is too low. Choice D, 110, is incorrect because it overestimates the total staff.