# Tricky math problem

nando94
Jerry drives 200 miles to work everyday from his house. While going there he drives at 50 mph. While coming back he drives at 25 mph. What was his average speed for the entire trip?

This question stumped me for 10 min.

Mentor
Out of curiousity, what did you get for the average speed?

Homework Helper
Gold Member
Jerry drives 200 miles to work everyday from his house. While going there he drives at 50 mph. While coming back he drives at 25 mph. What was his average speed for the entire trip?

This question stumped me for 10 min.

Yahhh, this question stumps me too since Jerry is driving 4 hours to get to work. Why is Jerry doing a job so far away? Then, 8 hours to drive back home. Jerry spends far too much time driving back and forth to this job. Jerry should find a job closer to home or relocate.

nando94
Out of curiousity, what did you get for the average speed?

I got 400/12 or 33.333

[2*Speed1*Speed2] / [speed1 + Speed2]

Thats the formula. Another way to do it is 50 + 50 + 50 + 50 + 25 + 25 + 25 + 25 + 25 + 25 + 25/12 or 400/12

At first I did 50+25/2 = 37.5 but thats the wrong answer since its asking the average for the entire trip. Thats when I realized that I had to add the entire distance traveled and divide it by the number in the set which is the arithmetic mean.

nando94
Yahhh, this question stumps me too since Jerry is driving 4 hours to get to work. Why is Jerry doing a job so far away? Then, 8 hours to drive back home. Jerry spends far too much time driving back and forth to this job. Jerry should find a job closer to home or relocate.

haha yeah thats true.