Correct Answer: A

Rationale: To find the average speed, first, convert 45 minutes to hours (45/60 = 0.75 hours). Then, divide the distance by the time: 5 miles · 0.75 hours = 6.67 mph. Choice A is correct because it accurately calculates the average speed based on the distance covered and time taken. Choice B is incorrect as it does not consider the time taken to cover the distance. Choice C is incorrect as it is higher than the calculated speed. Choice D is incorrect as it is higher and does not match the calculated average speed.

Correct Answer: C

Rationale: In this scenario, to find the total amount of medication administered in 3 hours, we first calculate the total drops administered by multiplying the drops per minute by the total minutes. This gives us 40 drops/minute * 180 minutes = 7200 drops. Then, we convert the drops to milligrams by multiplying the total drops by the amount of medication in each drop, which is 1mg. Therefore, 7200 drops * 1mg/drop = 7200mg. The correct answer is 7,200mg. Choice A is incorrect as it miscalculates the total amount. Choice B is incorrect as it doubles the correct answer. Choice D is incorrect as it quadruples the correct answer.

Correct Answer: A

Rationale: To add mixed numbers, first add the fractions: 1/8 + 1/4 = 3/8. Then, add the whole numbers: 3 + 1 = 4. Therefore, 3 1/8 + 1 1/4 = 4 3/8. Choice B (4 1/2) is incorrect because the fractions were not added correctly, leading to an incorrect result. Choice C (4 3/4) is incorrect as it does not represent the correct sum of the two mixed numbers. Choice D (5 1/4) is incorrect as it provides a result that is higher than the correct sum of the mixed numbers.

Correct Answer: A

Rationale: To produce 24 eggs in 24 hours, 4 times the number of chickens needed to produce 6 eggs is required. Since it takes 2 chickens to produce 6 eggs, 8 chickens are needed to produce 24 eggs in the same time frame. Choice B, 12 chickens, is incorrect because it doesn't consider the proportionality between chickens and eggs. Choice C, 18 chickens, is incorrect as it overestimates the number of chickens needed. Choice D, 6 chickens, is incorrect as it doesn't account for the increased number of eggs required.

Correct Answer: A

Rationale: To calculate 54% of $789.56, you multiply 0.54 by 789.56, which equals $426.36. Therefore, choice A, $426.36, is the correct answer. Choice B, $426.37, is incorrect as it is a slightly higher value. Choice C, $363.20, is incorrect as it is significantly lower than the correct answer. Choice D, $526.38, is incorrect as it is higher than the correct calculation result.