# Math Help - story problem

1. ## story problem

A virus scanning program is checking every file for viruses. It has completed checking 40% of the files in 300 seconds. How long should it take
to check all the files?

I think the answer is 420 second: 300 + 40% = 420

Can someone show me how to set up this proportion?

2. 300 is 40% of what?.

300=0.4x

3. Originally Posted by Patience
A virus scanning program is checking every file for viruses. It has completed checking 40% of the files in 300 seconds. How long should it take
to check all the files?

I think the answer is 420 second: 300 + 40% = 420

Can someone show me how to set up this proportion?
$\frac{40}{100} = \frac{300 \, s}{t}$

So after cross-multiplying:
$t = \frac{100}{40} \cdot (300 \, s) = 750 \, s$

-Dan