Two pipes A and B can fill a cistern in 37 1/2minutes and 45 minutes respectively. Both pipes are opened. The cistern will be filled in just half an hour, if the B is turned off after:

Two pipes A and B can fill a cistern in 37 1-div-1by2 minutes and 45 minutes respectively. Both pipes are opened. The cistern will be filled in just half an hour, if the B is turned off after:

[A].	5 min.
[B].	9 min.
[C].	10 min.
[D].	15 min.

Answer: Option B

Explanation:

Let B be turned off after x minutes. Then,

Part filled by (A + B) in x min. + Part filled by A in (30 -x) min. = 1.

x		2	+	1		+ (30 - x).	2	= 1
		75		45			75

	11x	+	(60 -2x)	= 1
	225		75

11x + 180 - 6x = 225.

x = 9.

Aptitude :: Pipes and Cistern : More Exercises

Pipes and Cistern- General Questions

Two pipes A and B can fill a cistern in 37 1/2minutes and 45 minutes respectively. Both pipes are opened. The cistern will be filled in just half an hour, if the B is turned off after:

Aptitude :: Pipes and Cistern : More Exercises

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