Question

While driving on the highway, Dave averages 60 miles per hour. In the city, he averages 30 miles per hour. On a trip to his grandmother's house, Dave drives 2 3/5 hours on the highway and 1 1/5 hours in the city.

Answer 1

The question: What is Dave's average speed for the entire trip to his grandmother's house? Round to the nearest tenth.

Answer 2

average speed = totaldistance/totaltime
since for each leg of the trip, distance = speed * time, we have


avgspeed = ((2 3/5 * 60)+(1 1/5 * 30))/(2 3/5 + 1 1/5)
= (156+36)/(3 4/5) = ?

Answer 3

So I got 50.52631..... and I rounded that to 50.5. Is this correct?