<PRE><B>Question 691720</B>
let the cold water faucet takes x min to fill the tub on its own 
so in 1 min it will fill 1/x part 
the hot water faucet takes 17 minutes to fill the tub by itself
so in 1 min it will fill 1/17 part 
so in 1 min the cold and hot water faucets will fill (1/x+1/17) part 
but the cold and hot water faucets take 7 minutes to fill the tub
so 1/x+1/17=1/7
or 1/x=1/7-1/17=(17-7)/17*7=10/119
or x=119/10=11.9 min
so the cold water faucet takes 11.9 min to fill the tub on its own 
ans</PRE>