The answer is 180, but what is the method?

Question

There are 245 children in a camp. If EACH child MUST be given 2 bottles of water a day and there are 18 bottles of water in one case, how many cases must be bought if the camp is to last for 5 days?

Answer 1

(245)(2) = 490 bottles per day.

490(5) = 2450 bottles needed for 5 days.

 

(2450 bottles)/(18 bottles/case) = 136.1 cases

 

If we can only buy in cases, we need 137 cases.

137(18)=2466 bottles. Each child gets their requisite

2 bottles per day and 16 bottles are left for the councillors.

 

180 cases would be 3240 bottles which is more

than we need.