Question

please answer this question..???

Answer 1

1/2-3/4= -1/4×60= -15

its your answer

Answer 2

Answer:

Pipe P1 can fill a tank in 1.5 hour

another pipe P2 empty it in 1.75 hour

How much time the tank be half filled

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Let tank's Volume be V

filling speed of pipe P1 = V/1.5 per hour = 2V/3 per hour  (A)

emptying speed of pipe P2 = V/1.75 = 4V/7 per hour   (B)

relative speed of filling a tank = (A) - (B) = V.(2/3 - 4/7 ) = 2V/21 per hour

hence,

tank would be filled in 21/2 = 10.5 hour

tank would be half filled in 10.5/2 = 5.25 hour = 5$\frac{1}{4}$ hour