Question

In what time would a cistern be filled by three pipes whose diameters are 1 cm, 113 cm, 2 cm, running together, when the largest alone will fill it in 61 minutes, the amount of water flowing in by each pipe being proportional to the square of its diameter? A32 minutes B34 minutes C36 minutes D38 minutes

Answer 1

Answer:

36 minutes

Step-by-step explanation:

The diameter of 3 pipes are 1 cm , 1 * 1/3 cm , 2 cm

They work together

Rate of pipes

1 x ² = 1 x

2² x = 4 x

4/3 ² x = 16/9 x

Rate of three pipes working together = 1 /N

So, N = x + 4 x + 16/9 x

  N = 61 x /9

Rate of the biggest pipe = 1/ 4x

1/4 x = 61 min

9 / 61 x = y min

y / 4 x = 9 /x

y × x = 36 x

y = 36

So the cistern be filled  in 36 minutes