25% is equal to 1/4 correct? (It is :D) So divide 972/4 to know what 25% of the school's population is. 972/4 = 243. So then 243 is 25% of the students. To get the 25% increase add 972 (for the students that will be back next year) and 243 (for the new students). I may have explained this in a really detailed way but it isn't that hard when you think about it!
When you square a number, you chose a number and multiplying itself. If you did the square root of 25, you would get 5. However if you divided 25 by 2, you would get 12.5 which is NOT the square root.
