Question

A house can fill the pool in 4 hours and another hose can fill the pool in 6 how long would it take to fill the pool with both hoses

Answer 1

(t / 4) + (t / 6) = 1

use 12 as common denominator ... (3 t / 12) + (2 t / 12) = 1

5 t / 12 = 1 ... 5 t = 12

Answer 2

Take the product of 2 numbers and divide by the sum of 2 number
(6×4)÷(6+4)
=2.4