Question

On Marlene's trip to Starved Rock, her average rate of speed for the entire five-hour trip was 62 miles per hour. For the first two hours of her trip, she kept her average speed at 50 miles per hour. Then she realized she was going to be late to meet her friend for dinner, so she started driving faster. What was her average speed for the last three hours of the trip?

Answer 1

70 miles per hour

Explanation:

Distance = speed * time

speed = distance / time

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Total Distance

speed = 62

time = 5

62 * 5 = 310 miles

Distance travelled in first 2 hours

speed = 50

time = 2

50 * 2 = 100 miles

Remaining distance

310 - 100 = 210 miles

Speed to cover 210 miles in 3 hours

distance = 210

time = 3

210/3 = 70 miles per hour