Thread: problem solving-brain twister

hey can sumone help me with this question...becasue i forgot how to do them..and its due tomorrow for school..any help will be great!! thanks in advance

Water from two hoses can fill a swimming pool in 4 hours. If each hose is used separately it takes 6 hours longer to fill the pool with the smaller hose than the larger hose. How long would it take to fill the pool if only the smaller hose is used.

thanx

PLEASE HELP

Originally Posted by phatjigga

hey can sumone help me with this question...becasue i forgot how to do them..and its due tomorrow for school..any help will be great!! thanks in advance

Water from two hoses can fill a swimming pool in 4 hours. If each hose is used separately it takes 6 hours longer to fill the pool with the smaller hose than the larger hose. How long would it take to fill the pool if only the smaller hose is used.

thanx

PLEASE HELP

Use the following law which makes this so much easier.

Hacker's Rule of Combine Work If a man does a job in A hours and a woman does a job in B hours then the combined work is:
AB/(A+B)


Now, let L be the amount of time for the large tube (in this case man). Let S be the amount of time for the small tube (in this case woman). Then,
(LS)/(L+S)=4
We also know that,
L+6=S

Substitute that into the equation,
[L(L+6)]/[L+(L+6)]=4
Thus,
(L^2+6L)/(2L+6)=4
Multiply by denominator,
L^2+6L=8L+24
Solve quadradic for positive root.
L=6
That means,
S=12.

This is Mine 48th Post!!!