Question

Kerri drives $150$ miles to visit her grandmother. She starts off driving $60$ miles per hour, but then encounters road construction and has to drive $20$ miles per hour the rest of the way. If she spends the same amount of time at the faster speed as at the slower speed, then how many hours did her $150$-mile trip take in total?

Answer 1

5 hours

Explanation:

-150 miles in all

-75 miles per speed

60 mph...

60 miles per hour over 75 miles

75 miles ÷ 60 miles = 1.25 hours

20 mph...

20 miles per hour over 75 miles

75 miles ÷ 20 miles = 3.75 hours

Total hours of driving...

60 mph for 1.25 hours

20 mph for 3.75 hours

3.75 hours + 1.25 hours = 5 hours total