Question

A red car left the park at 9 am. An hour later a blue car left the same park, heading to the same destination. If both cars arrived at the destination at 1 pm, and the speed of the blue car was 15 mph faster than the red car, what was the speed of the blue car?

Answer 1

Answer: 60 mph

Explanation:

Given

The red car left at 9 am and arrives at 1 pm

time taken by the red car
`t_a=4\ hr`

time taken by the blue car
`t_b=3\ hr`

Assume the speed of the red car is v

So, the speed of the blue car is v+15

distance traveled by them is the same

`\Rightarrow v* 4=(v+15)* 3\\\Rightarrow 4v=3v+45\\\Rightarrow v=45\ mph`

Thus, the speed of the blue car is
`45+15=60\ mph`