Remember that when posting questions here, you have to write the complete question in order to get a great and correct answer. Anyway, I found the complete question and is as follows:
A grading machine can grade 96 multiple-choice tests in 2 minute. How long will it take the machine to grade 300 tests?
So this problem can be used by using proportions. So we have that a grading machine can grade 96 multiple-choice tests in 2 minute. So we need to find the time (t) it takes the machine to grade 300 tests. So:
[tex]\frac{2}{96}=\frac{t}{300} \\ \\ Isolating \ t: \\ \\ t=300\frac{2}{96} \\ \\ t=6.25 minutes[/tex]
Hence, it would take the machine 6.25 minutes, that is, 6 minutes and 15 seconds to grade 300 tests.
