|
Question 900409: Amy, Bobby, and Candace are teaming up to paint a wall. If all three work together, it would take 80 minutes. If Amy and Candace work together, it would take 2 hours. If only Bobby and Candace work together, it would take 144 minutes. Suppose Amy and Bobby work together for 1 hour, then leave. If Candace arrives and must finish painting the wall by her self, how much longer will it take her to finish painting the wall?
Answer by richwmiller(17219)   (Show Source):
You can put this solution on YOUR website! 1/a+1/b+1/c=1/80,
1/a +1/c=1/120,
1/b+1/c=1/144,
1/120+1/b=1/80,
8/960+1/b=12/960
1/b=4/960
1/b=1/240
b=240
1/240+1/c=1/144
3/720+1/c=5/720
1/c=2/720,
c=360
1/a+1/360=1/120
1/a+1/360=3/360
1/a=2360=1/180
a=180= 3 hours
b=240= 4 hours
c=360= 6 hours
Suppose Amy and Bobby work together for 1 hour, then leave. If Candace arrives and must finish painting the wall by her self, how much longer will it take her to finish painting the wall?
60/180+60/240+x/c=1
1/3+1/4+x/360=1
4/12+3/12+x/360=1
7/12+x/360=1
x/360=5/12
x/360=150/360
x=150 minutes for Candace to finish 2.5 hours or 2 hours and 30 minutes
|
|
|
| |
