Question

A cistern generally takes 20 minutes to be filled by a pipe, but due to a leak, it takes 10 extra minutes to get filled. find the time in which the leak alone can empty the cistern filled the water

Answer 1

Pipe                                 time                                     portion of cistern

filling pipe                        20 mins                                      1 (whole )

filling pipe                            1 min                                      1/20

leak                                    x mins                                       1(empty)

leak                                       1 min                                      1/x

both                        (20+10) 30 mins                                    1(whole)

both                                       1 min                                       1/30

Now A/Q       1/30 = 1/20 -1/x

              ⇒ 1/x = 1/20 - 1/30 = 10/600

⇒  x = 60 mins

Therefore leak  would take 60 mins to empty that cistern.

Answer 2

Answer:

PIPE(P)=20 MINUTES TO FULL

LEAK(P-L)=30 MINUTES TO FULL

TOTAL CAPACITY LCM(20,30)=60

                                      P                      L                P-L

NO.OF MINUTES        20                      ?                 30

WORK DONE PER       (60/20)=3         -1                  (60/30)=2

MINUTES

NO. OF MINUTES=TOTAL CAPACITY/WORK DONE PER MINUTE

                              =60/1

                              =60

ANSWER 60

Step-by-step explanation: