What is the average speed of each?

Question

A light aircraft travels 6 miles per hour less than twice the speed of a car. If the car can travel 153 miles in the same time it takes the aircraft to travel 288 miles then what is the average speed of each?

aircraft:____miles per hour

car:_____miles per hour

Answer 1

Let the speed of car be c mph

 

Then speed of aircraft = 2c - 6

 

time = distance/average speed

 

time taken by car = 153/c

 

time taken by aircraft = 288/(2c-6)

 

since both times are equal then, 153/c = 288/(2c-6)

 

cross multiply; 153(2c-6) = 288c

 

306c - 918 = 288c; expanding

 

306c - 288c = 918; collecting like terms

 

18c = 918; dividing by 18 on both sides

 

c = 918/18 = 51 mph = speed of car

 

therefore speed of aircraft - 2c-6 = 2*51 - 6 = 96 mph

 

checking; 153/51 = 288/96 = 3 hours