It takes 5 mins to fill a twin size 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)?

The total volume of the twin size air mattress is 25593.75

It takes 5 minutes per 25593.75 cubed inches.

That is 5 over 25593.75, written like: 5/25593.75

The total volume of the queen sizes mattress is 42000.

It takes ? minutes per 42000 cubed inches.

That is ? over 42000, written like: ?/42000

Those are both proportions. We know those proportions will be equal. So, our problem is:

5/25593.75 = ?/42000

So solve this, we have to cross multiply and then solve the equation. We will substitute x for the question mark. The equation, after cross multiplying is:

25,593.75x = 210,000

Divide both sides by 25,593.75 to eliminate it.

x = 8.2

It takes 8.2 minutes to fill the queen sized air mattress. (If instructed to round to the nearest whole number, the answer would be 8.)

Let me know if you have any other questions about this! :)