If a car went the first third of the distance at 80 kmh, the second third at 24 kmh, and the last ...

If a car went the first third of the distance at 80 kmh, the second third at 24 kmh, and the last third at 44 kmh, what was the average speed of the car for the entire trip?

Quiz

Answer/Solution

39 kmh

Steps/Work

Assume D/3 = 2640 (this number is convenient because it is divisible by 80, 24 and 44)
So:
2640 = 80*T1 = 33 hrs
2640 = 24*T2 = 110 hrs
2640 = 44*T3 = 60 hrs
T = T1 + T2 + T3 = 203 hrs
D = RT
(2640*3) = R*203
R = 39
ANSWER: A

Physics Calculator / Auto Solver

If a car went the first third of the distance at kmh, the second third at kmh, and the last third at kmh, what was the average speed of the car for the entire trip?

Calculated Answer

39.014778325123

Step by Step Solution

In order to solve problem, you must evaluate 3 / (1 / n0 + 1 / n1 + 1 / n2).

n0 =80
n1 =24
n2 =44