Question

two pipes c and d can empty a full tank in 48 minutes and 72 minutes respectively if both tank simultaneoulsy then after how many minutes should pipe D be closed so that the tank is empty?
1) 27
2) 18
3) 24
4) 20​

Answer 1

${ \boxed{ \boxed{ \bold \red{27 \: minutes}}}}$

Step by Step

Two pipes X and Y can individually fill a tank in 48 and 72 minutes respectively.

Part of tank filled by X and Y together in 1 hour = 1/48 + 1/72 = (3 + 2)/144 = 5/144

∴ Time taken by both the pipes to fill the tank = 144/5 =27 or 28.8 minutes

Answer 2

Answer:

Concept:

       Another framework for time- and work-based inquiries is pipes and cistern. Questions about how long it takes to fill or empty a tank, how much work is involved in the process, and other similar inquiries may be made .An inlet is a conduit that is linked to a tank to fill it with water. This kind of work has been accomplished. An exit is a conduit that is connected to empty the water from the tank. This suggests that the work was of a negative nature. In the query, it may also be referred to as "leak."

Step-by-step explanation:

Given:

Two pipes C and D can empty a full tank in 48 minutes and 72 minutes respectively.

To find:

After how much time should pipe D be taken to close the tank to be empty.

Solutions:

Let part of tank filled by C is taken as $\frac{1}{48}$ minutes.

Let part of tank filled by D is taken as $\frac{1}{72}$ minutes.

Part of tank filled by both C and D together = $\frac{1}{48}$ + $\frac{1}{72}$

                                                                         = $\frac{5}{144}$

Time taken by both the pipes to fill the tank = $\frac{144}{5}$

                                                                           =27 or 28.8 minutes.

Hence the option (1) is correct.

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