# Two pipes A and Y can fill a cistern in 24 min. and 32 min

Two pipes A and Y can fill a cistern in 24 min. and 32 min. respectively. If both the pipes are opened together, then after how time Y should be closed so that the tank is full in 18 minutes?

(a) 6 min

(b) 8 min

(c) 10 min

(d) 12 min

**Answer: (b) 8 min **

**Solution:-**

Let B be closed after X min.

then , part filled by (A+B) in X min. + part filled by A in (18-X)min.=1

Therefore, X x ((1/24)+(1/32))+(18-x) x (1/24)=1 6 (7 X/96) + ((18-X)/24)=1.

ó7 X +4 x (18-X)=96.

Hence, be must be closed after 8 min.