Q) Two pipes together can fill a tank in \frac{15}{8} hours. The pipe with larger diameter takes 2 hours less than the pipe with smaller diameter to fill the tank separately. Find the time in which each pipe can fill the tank separately.

Ans:

Two water taps together can fill a tank CBSE 2023-24 sample paper

Let’s consider the larger pipe takes X hours to fill the tank separately

hence, smaller pipe will take pipe X + 2 hours

Therefore, time taken together to fill the tank:

\frac{1}{\times} + \frac{1}{\times + 2} = \frac {8}{15}    (given)

15 [(X + 2) + X ] = 8 X (X + 2)

30 X +30 =  8X2 + 16X

4X2 – 7 X – 15 = 0

4X2 – 12 X + 5 X – 15 = 0

(X – 3) (4X + 5) = 0

Since x \neq - \frac{5}{4}, therefore X = 3

and X + 2 = 5

Therefore, the pipe with larger diameter will take 3 hrs and smaller diameter pipe will take 5 hrs to fill the tank separately.

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