Answer:

(I)4hours

Step-by-step explanation:

(I)Tap A fills in 2 hours

so tank filled by tap A in 1 hour = 1/2

Tap B empty it in 4 hours

so tank emptied in 1 hour = 1/4

tank filled in 1 hour = -1/4

Tank filled in 1 hour when A and B both are open

= 1/2 + ( -1/4 ) = 1/4

so time required to fill tank by both taps opened is 4 hours

(ii) Tap A fills in 2 hours

Tank filled by A in hour = 1/2

Tank emptied in an hour = -1/2

Tap B empties it in 4 hours

Tank emptied by B in an hour = 1/4

Tap C empties it in 6 hours

Tank emptied by C in an hour = 1/6

Tank emptied in an hour with all taps opened

= -1/2 + 1/4 + 1/6 = ( -6 + 3 + 2 )/12

= -1/12

since in an hour it will be filled 1/12 so it's not possible to get empty with all taps open

Answer:

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