Question

A jet plane flew at an average speed of 240 mph going from city A to city B and averaged 300 mph on the return flight. Its return flight took 1 hour 40 minutes less time. How far is it from city A to city B? (Disregard any wind.)

Answer 1

First step is to mph into miles:

Turn 1hr and 40 min into a decimal:

1hr 40min ----> 1.6667hr

Then multiply:

300 x 1.6667 = 500.1

The distance is 500.1 miles.

Hope this helps!

Answer 2

Use distance = rate × time

The first trip is:
d = 240 x t₁

The second trip is:
d = 300 × t₂

The relationship between t₁ and t₂ is:
t₂ = t₁ - 1 hour 40 minuites
(1 hour 40 minutes converted to hours is 1 2/3 or 5/3 hours), so:
t₂ = t₁ - 5/3

Now substitute:

d = 240t₁
d = 300(t₁ - 5/3) = 300t₁ - 500

Set both equations equal to each other and solve:

240t₁ = 300t₁ - 500
500 = 60t₁
8 1/3 = t₁
25/3 = t₁

Now plug in to solve for d:

d = 240×25/3 = 2000

So the distance from city A to city B is 2000 miles.