Question

it takes 30 kids 6 hours to build a man sized Sand Castle. how many kids were there if the same game took only two-and-a-half hours ​

Answer 1

There were 72 kids there.

Explanation:

This question can be solved using proportions, by a rule of three.

The number of kids and time are inversely proportional, that is, if we increase the number of kids to build the castle, the time it takes will decrease. This means that to solve the rule of three, instead of applying cross multiplication, we apply line multiplication.

We have that:

30 kids - 6 hours

x kids - 2.5 hours.

Applying line multiplication

`2.5x = 30*6`

`x = (180)/(2.5)`

`x = 72`

There were 72 kids there.