Question

it takes an air pump 4.0 minutes to fill a twin sized air mattress (39 by 8.75 by 75 inches). How long will it take to fill a queen sized mattress (60 by 8.75 by 80 inches)?

Answer 1

Volume of twin sized mattress =

39* 8.75* 75 = 25593.35 cubic inch

Volume of queen sized mattress =

60* 8.75* 80 = 42000 cubic inch

To fill 25593.35 cubic inch it takes 4 minutes

To fill 1 cubic inch it will take = $\frac{4}{25593.35}$ minutes

So to fill 42000 cubic inch it will take = $\frac{4}{25593.35} * 42000$

= 6.56 minutes.