The surface 5 cm, and the length is 10 cm
Let us assume the length of a side of the square floor = x feet
Area of the square floor as given in the question = 320 square feet
Then
x^2 = 320
x^2 = (17.89)^2
Then
x = 17.89
= 18 feet approx
From the above deduction, it can be easily concluded that the correct option among all the options that are given in the question is the second option or option "B".
To find the lateral surface area of a pyramid, you can find the area of each triangle, A = 1/2bh or A = 1/2lw, then multiply by the number of triangles, which would be based on the number of sides of the base; or you can take half the perimeter and multiply by the slant height.
7 > z + 18 ≥ 6
Subtract 18 from all 3 parts:
7-18 > z +18 -18 ≥ 6-18
-11 > z ≥ -12