Solve Time for Tank Filling with 2 Pipes

[pat666]

Homework Statement

"A tank can be filled in 6 hours using 2 pipes. The larger pipe alone would fill it 5 hours sooner than the smaller pipe alone. How long would each pipe alone take?"

Homework Equations

I know it involves a quadratic not sure on the rest... I can't see how to do with a quadratic i mean.

The Attempt at a Solution

assume a is the big pipe and b is the small
A+B=6
A=B+5 solved them to get a=11/2hours and b=1/2, i can see that's not right. i said that a was the bigger one and my answer says that its not?

 

[Aceterp]

Homework Statement

"A tank can be filled in 6 hours using 2 pipes. The larger pipe alone would fill it 5 hours sooner than the smaller pipe alone. How long would each pipe alone take?"

Homework Equations

I know it involves a quadratic not sure on the rest... I can't see how to do with a quadratic i mean.

The Attempt at a Solution

assume a is the big pipe and b is the small
A+B=6
A=B+5 solved them to get a=11/2hours and b=1/2, i can see that's not right. i said that a was the bigger one and my answer says that its not?

This website may help you

http://www.algebra.com/algebra/home...ems/HOW-TO-Solve-Rate-of-Work-Problems.lesson


So using the the equation form the website you get

1/a + 1/a+5 = 1/6

This simplifies to

(2a+5)/a(a+5) = 1/6

which simplifies down to the quadratic a^2 – 7a -30 = 0

 

[pat666]

ok thanks