PSAT Math Multiple-Choice Question 149: Answer and Explanation

Question: 149

A team of scientists is tracking a snail moving at a rate of 700 millimeters per minute. If there are 10 millimeters in a centimeter, at what rate does that snail move in centimeters per hour?

• A. 4,200
• B. 7,000
• C. 42,000
• D. 420,000

Correct Answer: A

Explanation:

A

The question asks for the rate of the snail in centimeters per hour. Begin by reading the question to find information on the snail's pace. The question states that the snail moves at a rate of 700 millimeters per second. Convert the 700 millimeters into centimeters. Since there are 10 millimeters in 1 centimeter, set up the proportion . Cross-multiply to get 10x = 700. Divide both sides by 10 to get x = 70. Therefore, the snail moves at a rate of 70 centimeters per minute. Determine the number of centimeters travelled in 1 hour. Since there are 60 minutes in 1 hour, set up the proportion . Cross-multiply to get y = 4,200. Therefore, the snail moves at a rate of 4,200 centimeters per hour. The correct answer is (A).