Question

A swimming pool can be filled by pipe A in $3$ hours and by pipe B in $6$ hours, each pump working on its own. At $9am$ pump A is started. At what time will the swimming pool be filled if pump B is started at $10am$?

Answer 1

At $10am$ $Volume=\frac{V}{3}$

At $(10+t)am$(When tank is full)

$V=\frac{V}{3}+(\frac{V}{3}+\frac{V}{6})t$

$1=\frac{1}{3}+(\frac{1}{3}+\frac{1}{6})t$

$t=\frac{4}{3}hrs=1:20hrs$

That Means Swimming will be filled at $10:00+1:20=11:20$