Answer:
The correct option is (a).
Step-by-step explanation:
The complete question is:
A hose can fill a swimming pool in 6 hours. Another hose needs 3 more hours to fill the pool than the two hoses combined. How long would it take the second hose to fill the pool.
Solution:
The first hose takes 6 hours to fill the pool.
So, work done per hour by the first hose is, 1/6.
Suppose the second hose takes x hours to fill the pool.
So, work done per hour by the second hose is, 1/x.
The work done per hour by the two hoses together is, [1/6 + 1/x] = (x + 6)/6x.
Together the two hoses can fill the pool in, 6x/(x + 6) hours.
It is provided that, the second hose needs 3 more hours to fill the pool than the two hoses combined.
That is:
6x/(x + 6) = x - 3
6x = (x - 3)(x + 6)
6x = x² + 3x - 18
x² - 3x - 18 = 0
x² - 6x + 3x - 18 = 0
x (x - 6) + 3 (x - 6) = 0
(x + 3)(x - 6) = 0
x = 6
Then the time taken by the two hoses together is,
6x/(x + 6) = x - 3 = 6 - 3 = 3 hours
So, each hose takes 6 hours and together they take 3 hours to fill the pool.
This implies that the second hose takes 3 hours more than the 3 hours together to fill the pool.
Thus, the correct option is (a).