GeminiHeat wrote:
A closed rectangular box with a square base is 5 inches in height. If the volume of the box is 45 square inches, what is the box’s surface area in square inches?
(A) 45
(B) 66
(C) 78
(D) 81
(E) 90
This is how I did it!
We do not know if the sides are integers or not\(Volume = lbh\)
\(45 = 5lb\)
\(lb = 9\)
\(T.S.A = 2(lb + bh = lh)\)
\(= 2(9 + 5b + 5l)\)
\(= 18 + 10(l + b)\)
We are looking for an option choice which is divisible by \(10\) when \(18\) is subtracted from it!
Only C Matches
\(78 - 18 = 60\) and is divisible by \(10\)
Hence, option C