Question

Racer's average driving speed

for a 4-hour trip was 45 miles per
hour. During the first three hours he
drove 40 miles per hour. What was his
average speed for the last hour of his
trip?
A 70 miles per hour
B. 60 miles per hour
C. 50 miles per hour
D. 65 miles per hour

Answer 1

so to average 45mph for 4 hours, he had to drive 4x45 miles total

4x45= 180miles

now we know he drove 120 miles (3x40) in the first 3 hours.

so he drove 180-120= 60 miles in the last hour.

60mph

Answer 2

the answer is C.

Explanation:

(50+40)/2=45