A car travels at 60 mph for 2 hours and 50 mph for 1 hour. What is the average speed for the trip?

Prepare for the PSAT 8/9 Math Test. Engage with flashcards and multiple-choice questions, featuring hints and explanations for each question to help you succeed. Be exam-ready!

Multiple Choice

A car travels at 60 mph for 2 hours and 50 mph for 1 hour. What is the average speed for the trip?

Explanation:
Average speed is total distance traveled divided by total time. The car goes 60 mph for 2 hours, which is 120 miles, and 50 mph for 1 hour, which is 50 miles. So total distance is 170 miles and total time is 3 hours, giving an average speed of 170 ÷ 3 ≈ 56.7 mph. This is why you don’t just average the speeds; each speed lasts a different amount of time, so you weight by time. (A simple arithmetic mean of the speeds would give 55 mph, which ignores the longer time at the higher speed.)

Average speed is total distance traveled divided by total time. The car goes 60 mph for 2 hours, which is 120 miles, and 50 mph for 1 hour, which is 50 miles. So total distance is 170 miles and total time is 3 hours, giving an average speed of 170 ÷ 3 ≈ 56.7 mph. This is why you don’t just average the speeds; each speed lasts a different amount of time, so you weight by time. (A simple arithmetic mean of the speeds would give 55 mph, which ignores the longer time at the higher speed.)

More Multiple Choice Questions
Subscribe

Get the latest from Passetra

You can unsubscribe at any time. Read our privacy policy