Question

Bill spends two days driving from Point A to Point B . On the first day, he drove 2 hours longer and at an average speed 5 miles per hour faster than he drove on the second day. If during the two days he drove a total of 680 miles over the course of 18 hours, what was his average speed on the second day, in miles per hour?

A) 20
B) 25
C) 28
D) 30
E) 35

Answer 1

His average speed on the second day is 35 miles per hour.

Explanation:

Consider the provided information.

On first day, he drove 2 hours longer than he drove on second day.

Let x = Number of hours he drove on second day.

Then x + 2 = Number of hours he drove on first day.

It is given that he drove a total of 18 hours.

Therefore,

`x + (x + 2) = 18`

`2x + 2= 18`

`x=8`

He drove 8 hours on second day.

x + 2 = 8+2=10

He drove 10 hours on first day.

Let y = speed driven on second day.

y + 5 = speed driven on first day.

As we know: Distance = speed × time

On first day he covers a distance of:

Distance = 10(y+5)

On second day he covers a distance of:

Distance = 8(y)

Total distance = Day 1 distance + Day 2 distance

`10(y+5) + 8(y) = 680\\10y+50+8y=680\\18y=630\\y=35`

Hence, his average speed on the second day is 35 miles per hour.