It takes thirty kids four hours to build a man-sized sand castle.How many kids were there if the same game took only two and a half hours?

The problem is about the relationship between the number of kids and the time it takes to build the sand castle. This is an inverse relationship, meaning that as the number of kids increases, the time it takes to build the sand castle decreases.

Step 1: Understand the initial situation Initially, we know that 30 kids can build the sand castle in 4 hours.

Step 2: Understand the changed situation The time to build the sand castle has decreased to 2.5 hours, and we need to find out how many kids were there in this situation.

Step 3: Set up the relationship We can say that the number of kids is inversely proportional to the time it takes to build the sand castle. This can be written as: Kids1/Time1 = Kids2/Time2

Step 4: Plug in the known values and solve for the unknown So, we can plug in the known values and solve for the unknown number of kids in the second situation: 30 kids / 4 hours = Kids2 / 2.5 hours Solving this equation gives: Kids2 = (30 kids * 2.5 hours) / 4 hours = 18.75 kids

Since we can't have a fraction of a kid, we'll round this up to the nearest whole number. So, there were 19 kids when the game took only two and a half hours.