If a mixture of 24 lb. of cement, 48 lb. of sand, and 63 lb. of gravel is needed to make 1 cubic foot of concrete, how many pounds of sand are needed to pour a pool deck of 156 cubic feet?

This is a ratio problem. You only need solve the ratio of the sand. 

  48   =    n       
    1        156

(48)(156) = 1(n)   (cross multiplying) 

7,488 pounds

To check: The pool deck is 156 times larger than the original amount of concrete so the amount of sand needs to be 156 times more.