Algebra

[Guest]

A cargo plane leaves an airport and travels east at 380 miles per hour. Two hours later a jet plane leaves the same airport and travels in the same direction at 900 miles per hour. How long will it take the jet plane to catch up to the cargo plane?

 

[TchrQbic]

A cargo plane leaves an airport and travels east at 380 miles per hour. Two hours later a jet plane leaves the same airport and travels in the same direction at 900 miles per hour. How long will it take the jet plane to catch up to the cargo plane?

This problem can be solved using the distance = rate*time fact, and recognizing that when the jet catches up to the other plane, they will have gone EQUAL distances.

1) pick variables and represent the given information
2) express the relationship with an equation (distance₁ = distance₂)
3) solve

 

[soroban]

Hello, berrettm!

A cargo plane leaves an airport and travels east at 380 mphr.
Two hours later a jet plane leaves the same airport and travels in the same direction at 900 mph.
How long will it take the jet plane to catch up to the cargo plane?

Here's a back-door approach that your teacher won't appreciate, I'm sure.

The cargo plane has a two- hour headstart; it is already 760 miles ahead.

The jet plane flies at 900 mph.
The difference of their speeds is: \(\displaystyle \,900\,-\,380\:=\:520\) mph.

It is as if the cargo plane has stopped and the jet is following at 520 mph.

To cover the 760 miles, it will take: \(\displaystyle \:\frac{760}{520}\:=\:\frac{19}{13}\) hours.

 

[Denis]

Soroban, it takes less time to enter a house from the front door
than from the back door; so yours is the front door approach :wink: