2007-10-19 18:03:07 · 11 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Let X = area to be washed.
____________Monica_____Bill
Work rate_____X________X/2
Working together work they clean (3/2)X in 1 hour
(3/2) X<---> 1 hour
X<--------->X / (3/2)(X) hour = 2/3 hour
It will take them 40 min
2007-10-19 19:55:52 · answer #1 · answered by Como 7 · 0⤊ 0⤋
monica can do 1 car per hour
bill can do 1/2 a car per hour
so together they can do 1 and a half cars per hour
or 3/2 cars/hour
so (1 car)/ (3/2 cars/hour)= 2/3 hour.
Together they can wash a car in 2/3 hour.
or 2/3 hours * 60 min/hour= 40 minutes
2007-10-20 01:13:39 · answer #2 · answered by zenock 4 · 0⤊ 0⤋
Let x be the part of the job done
x/1 + x/2 = 1
(3/2)x = 1
x = 2/3
it will take them 40 minutes to wash one car
2007-10-20 01:12:18 · answer #3 · answered by rEi 3 · 0⤊ 0⤋
Bill's rate is 1/(2 hr/car) or .5 car/hour
Monica's rate = 1 car/hour
Monica + Bill rate together = 1 car/hour + .5 car/hour
= 1.5 car/hour
Rate (Time) = # of cars washed
1.5 car/hr (time) = 1 car Divide both sides by 1.5
time = 1 car / (1.5car/hr)
time = .666666667 hours
Convert to Minutes
= .666666667 hours (60 minutes/hour)
= 40 minutes ANSWER
2007-10-20 01:11:00 · answer #4 · answered by r r 5 · 1⤊ 0⤋
1/1 + 1/2 = 1/x where x = time for both doing this together
3/2 = 1/x
3x = 2
x = 2/3 hr
2007-10-20 01:12:56 · answer #5 · answered by duffy 4 · 0⤊ 0⤋
40 minutes
2007-10-20 01:11:17 · answer #6 · answered by Anonymous · 0⤊ 0⤋
tell them to both wash 1 car and time them.
2007-10-20 02:51:27 · answer #7 · answered by seaniquanzo 2 · 0⤊ 0⤋
40 minutes.
2007-10-20 01:12:14 · answer #8 · answered by crazyramsfan 1 · 0⤊ 0⤋
2 hours...Why would Monica wash the car when she can get Bill to do it???? Silly Rabbit!!!!
2007-10-20 01:08:48 · answer #9 · answered by imshorty 2 · 1⤊ 1⤋
If they are washing at the same time, two hours.
2007-10-20 01:07:53 · answer #10 · answered by Nicole L 3 · 0⤊ 1⤋