Question

Doug’s average driving speed is 1 kilometers per hour faster than Thor’s. In the same length of time it takes Doug to drive 390 kilometers, Thor drives only 384 kilometers. What is Doug’s average speed?

Answer 1

Answer:

Doug speed will be 65 km/hr

Explanation:

Let the Thor's speed is x km/hr

So Doug's speed = x+1 km/hr

We have given that Doug and Thor take same time to cover 390 km and 384 km respectively

We know that time is given by

$time=\frac{distance}{speed}$

So time taken by Doug to cover the distance

$time=\frac{390}{x+1}$

And time taken by Thor to cover the distance

$time=\frac{384}{x}$

As both times are equal

So $\frac{390}{x+1}=\frac{384}{x}$

$6x=384$

$x=64km/hr$

So Doug speed will be 64+1 = 65 km/hr