SOLUTION: officils begin to empty a man made lake at a rate that wouldempty the lake in 18 weeks but a river that can fill the lake in 30 weeks is replenishing the lake at the same time, how

Algebra ->  Rate-of-work-word-problems -> SOLUTION: officils begin to empty a man made lake at a rate that wouldempty the lake in 18 weeks but a river that can fill the lake in 30 weeks is replenishing the lake at the same time, how      Log On


   



Question 945758: officils begin to empty a man made lake at a rate that wouldempty the lake in 18 weeks but a river that can fill the lake in 30 weeks is replenishing the lake at the same time, how long would it take to empty the lake
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
officials begin to empty a man made lake at a rate that would empty the lake in 18 weeks
but a river that can fill the lake in 30 weeks is replenishing the lake at the same time,
how long would it take to empty the lake
:
let t = time to empty the lake in this scenario
let the completed job = 1 (an empty lake)
:
t%2F18 - t%2F30 = 1
Multiply equation by 90
90*t%2F18 - 90*t%2F30 = 1(90)
Cancel the denominators
5t - 3t = 90
2t = 90
t = 45 weeks to empty the lake