Question

On a trip, a motorist drove 150 miles in the morning and 50 miles in the afternoon. His average rate in the morning was twice his average rate in the afternoon. He spent 5 hours driving. Find his average rate on each part of the trip.
pls help

Answer 1

Answer:

Morning's average rate = 50 mph, and Afternoon's average rate = 25 mph.

Step-by-step explanation:

Suppose he drove 150 miles for X hours, then his average rate in the morning was (150/X) mph.

Given that he spent 5 hours in driving.

And he drove 50 miles for (5-X) hours, then his average rate in the afternoon was 50/(5-X) mph.

Given that his average rate in the morning was twice his average rate in the afternoon.

(150/x) = 2 * 50/(5-x)

150/x = 100/(5-x)

Cross multiplying terms, we get:-

150*(5-x) = 100*x

750 - 150x = 100x

750 = 100x + 150x

750 = 250x

x = 750/250 = 3.

It means he spent 3 hours in the morning and 2 hours in the afternoon.

So morning's average rate = 150/3 = 50 mph.

and afternoon's average rate = 50/(5-3) = 25 mph.