Chapter 6.4, Problem 4P

Solve each word problem

One plane at 520 feet is ascending at a rate of 40 feet per minute, while another plane at 3800 feet is descending at a rate of 120 feet per minute. How long will it take the two planes to be at the same altitude?

To determine

To solve given word problem.

Answer to Problem 4P

In 20.5 minutes they will be at same altitude.

Explanation of Solution

Given information :

One plane is at 520 ft. is ascending at a rate of 40 feet per minute.

Another plane is at 3800 feet is descending at rate of 120 minutes.

Let the time in minute when the both plane will be at same altitude be x .

Hence the equation becomes,

  $520+40x=3800-120x$

Now we shall solve for x .

We get,

  $\begin{array}{l}520+40x=3800-120x\\ 40x+120x=3800-520\\ 160x=3280\\ x=\frac{3280}{160}=20.5\end{array}$

Hence in 20.5 minutes they will be at same altitude.