Question

Jeremy is making a 665 mile trip. He drives for 5 hours at 55 mph. What is the average rate of speed he must drive to complete the TOTAL trip in 11 hours? Assume that a steady speed is maintained for the rest of the trip.

Answer 1

Answer:the formula to calculate average speed is :

average speed= total distance/elapsed time .

He drives 5 hours at 55 mph so we need to calculate first how far or the distance he has driven at the moment hence from the above formula d= rt ( r stand for speed and t stand for time while d stand for the distance)

d=rt

d= 55*5= 275 mph this is how far he has driven at the moment.

So to see how many miles left we subtract the miles he has covered to the total miles he has to cover ;

d =665-275= 390

He also want to cover this trip in 11 hours but he has already driven for 5 hours hence time= 11 - 5 = 6 hours left

So now we have d= 390 and t = 6

So now using the same formula we now need to find the average speed which is ' r' in the formula

d = rt

390=r*6

390/6=r

r = 65mph

hence he will have to drive 65 mph to complete his trip in 11 hours.