Question

A sandpit in the shape of a rectangular prism has length 7 feet, width 5 feet, and height 1.75 feet. It is filled to the brim with sand. Joe puts this sand into a second sandpit having the same shape but a larger base. He needs 17.5 cubic feet of sand to fill the extra space inside the second sandpit.

If the height of the two sandpits is the same, what are the dimensions of the base of the second sandpit?
Answer

5 feet x 2 feet

10 feet x 7 feet

9 feet x 5 feet

20 feet x 25 feet

Answer 1

volume of first one is 7*5*1.75=61.25 cubic feet
and it needs 17.5 cubic feet extra sand so, the volume of second one is
61.25+17.5=78.75 cubic feet is has same height as first one
so the area of base is 78.75/1.75=45
which only satisfy 9 feet x 5 feet
the third selection

Answer 2

thank-you!!