Question

Working together, it takes two computers 5 minutes to send out a company's email. If it takes the slower computer 15 minutes to do the job on its own, how long will it take the faster computer to do the job on its own?Do not do any rounding.

Answer 1

Given:

Working together, it takes two computers 5 minutes to send out a company's email. If it takes the slower computer 15 minutes to do the job on its own

Let the faster computer has a rate of x emails per minute

And the slower computer has a rate of y emails per minutes

And let the total mails = z

When the two computers working together, the time taken to send the mails = 5 minutes

So,

$x+y=\frac{z}{5}\rightarrow(1)$

And the slower computer 15 minutes to do the job on its own

So,

$y=\frac{z}{15}\rightarrow(2)$

substitute equation (2) into equation (1)

$\begin{gathered} x+\frac{z}{15}=\frac{z}{5} \\ x=\frac{z}{5}-\frac{z}{15}=\frac{2z}{15} \end{gathered}$

So, the answer will be:

The faster computer will do the job in a time = 15/2 = 7.5 minutes