Answer: Option C
Explanation:
Let the cistern be filled by pipe A alone in x hours.
Then, pipe B will fill it in (x + 6) hours.
|
1 |
+ |
1 |
= |
1 |
x |
(x + 6) |
4 |
|
x + 6 + x |
= |
1 |
x(x + 6) |
4 |
x2 - 2x - 24 = 0
(x -6)(x + 4) = 0
x = 6. [neglecting the negative value of x]