If two pipes function simultaneously , a reservoir will be filled in 12 hrs.one pipe fills the reservoir 10 hrs faster than the other.how many hrs will the second pipe take to fill the reservoir?
let the reservoir be filled by first pipe in x hours.
Then ,second pipe fill it in (x+10)hrs.
Therefore (1/x)+(1/x+10)=(1/12) <=>(x+10+x)/(x(x+10))=(1/12).
x^2 –14x-120=0 <=> (x-20)(x+6)=0
<=> x=20 [neglecting the negative value of x]
so, the second pipe will take (20+10)hrs. (i.e) 30 hours to fill the reservoir