Question

There are 3 minutes ofcommercials for every15 minutes of television.How many minutes ofcommercials are there in1 hour and 20 minutes oftelevision?

Answer 1

For every 15 minutes, there are 3 minutes of commercials We can write this as

$\frac{3\text{ min commerical}}{15\text{minutes}}$

Now in one hour, there are 60 minutes; therefore, in 1 hour and 20 minutes, there are 60+ 20 = 80 minutes.

Let us call x the number of minutes in these 80 minutes, then we have the equation

$\frac{3\text{ min commerical}}{15\text{minutes}}=\frac{x\text{ min commerical}}{80\text{minutes}}$

which says that the ratio of commercial minutes and the television minutes must remain constant.

Cross multiplication gives

$3\cdot80=x\cdot15$$\rightarrow15x=240$

dividing both sides by 15 gives

$x=16.$

Hence, in 1 hour and 20 minutes, there are 16 minutes of commercial.