Find the are of the pool by dividing the volume by the depth:
1960 / 4 = 490
The pool is 490 square feet.
Area is found by multiplying the length by the width.
Let the width = X
We are told the length is 2.5X ( 2.5 times longer)
So we now have 2.5x * x = 490
2.5x * x = 2.5x^2
Now we have 2.5x^2 = 490
Divide both sides by 2.5:
x^2 = 490/2.5
x^2 = 196
find X by taking the square root of 196:
x = √196
x = 14
The width is 14 feet
The length is 2.5 * 14 = 35 feet