Question

2 pipes can fill a cistern in 3 minutes. if the larger pipe takes 4 minutes lesser than the smaller pipe to fill the cistern, how much time does the smaller pipe take to fill the cistern?

Answer 1

let the time taken by 1st pipe be x
time taken by 2nd pipe=x-4
cistern filled by 1st pipe in 1min is 1/x
cistern filled by 2nd pipe in 1min is 1/x-4
1/x-4+1/x=1/3
x+x-4/x(x-4)=1/3
3(2x-4)=x^2-4x
6x-12=x^2-4x