SOLUTION: What is the average rate, in miles per hour, of a car that travels 20 miles at 40 miles per hour and then 10 miles at 60 miles per hour? I also need a formula to along with this

Algebra.Com
Question 821094: What is the average rate, in miles per hour, of a car that travels 20 miles at 40 miles per hour and then 10 miles at 60 miles per hour?
I also need a formula to along with this. Thank you!

Answer by TimothyLamb(4379)   (Show Source): You can put this solution on YOUR website!
time per leg:
t = d / s
t = 20/40 + 10/60
t = 1/2 + 1/6
t = 6/12 + 2/12
t = 8/12
---
avg speed:
s = d / t
s = (20 + 10)/(8/12)
s = (30)/(8/12)
s = 45 mph
---
NOTE:
avg speed is NOT: (40+60)/2=50
---
Solve and graph linear equations:
https://sooeet.com/math/linear-equation-solver.php
---
Solve quadratic equations, quadratic formula:
https://sooeet.com/math/quadratic-formula-solver.php
---
Solve systems of linear equations up to 6-equations 6-variables:
https://sooeet.com/math/system-of-linear-equations-solver.php

RELATED QUESTIONS

A man travels a distance of 20 miles at 60 miles per hour and then returns over the same... (answered by stanbon)
If a motorcycle driver travels 40 miles at m miles per hour and then 50 miles at m + 10... (answered by Fombitz)
a motorcyclist travels 90 miles at rate of 20 miles per hour, if he returns same distance (answered by mananth)
A car traveled 10 miles at an average speed of 20 miles per hour and then traveled the... (answered by jorel1380)
A car travels 60 miles in the same time that a car traveling 10 miles per hour faster... (answered by Theo)
A man travels a certain distance at 60 miles per hour and returns over the same road at... (answered by Alan3354)
A car travels 60 miles in the same time that a car traveling 10 per hour faster travels... (answered by ptaylor)
a car travels at the rate of 45 miles per hour and averages 25 miles per gallon of... (answered by texttutoring)
I am confused about this question. In the book it says that the average is not 50 miles... (answered by Mathtut)