You check on manufactured parts in a factory. You need to take measurements to ensure quality. According to the drawing shown, the measurement of dimension A is: 1/2'' + 1/4'' + A = 2''; A = 2'' - 1/2'' - 1/4''; A = 1 1/4''.

You need to pump water out of a flooded basement, using two 50 - gallon-per-minute (GPM) pumps. The basement has the dimensions shown and is flooded to a depth of 16 inches. It will 199.48 min take to pump the water out of the basement.
Solution:
V = length x width x depth; length = 50 feet;
width = 40 feet;
depth = 16 inches ( 1 foot / 12 inches ) = 1.33 feet;
V = 50 x 40 x 1.33
= 2666.67 ft^3
= 19948.05 gal;

Time = V / rate;
= 19948.05 gal / 100 gal / min;
= 199.48 min.