How long will they take together to wash 1000 dishes?
2007-07-01 15:58:15 · 15 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
set up an equation
1000=hours(the rate ben washes + the rate frank washes)
1000=hours(500/2 + 450/3)
1000=hours(250 + 150)
1000=hours(400)
2.5=hours
theoretically at least, they may not actually do that when together
2007-07-01 16:03:37 · answer #1 · answered by lizzyhappy2007 2 · 1⤊ 0⤋
Ben takes 2 hours to wash 500 dishes, Frank takes 3 hours to wash 450 dishes. How long will they take together to wash 1000 dishes?
Ben washes
500/2 = 250 dishes/hour
Frank washes
450/3 = 150 dishes/hour
Together they wash
250 + 150 = 400 dishes/hour
Time to wash 1000 dishes
1000/400 = 2.5 hours or 2 hours and 30 minutes
2007-07-01 23:33:11 · answer #2 · answered by Northstar 7 · 0⤊ 0⤋
Ben washes 500 dishes / 2 hours = 250 dishes / 1 hour.
Frank washes 450 dishes / 3 hours = 150 dishes / 1 hour.
dishes that Frank washes in x hours + dishes that Ben washes in x hours = 1000 dishes
250x + 150x = 1000
400x = 1000
x = 2.5
Answer: 2.5 hours
2007-07-01 23:11:00 · answer #3 · answered by mathjoe 3 · 0⤊ 0⤋
Ben takes 4hours alone to wash 1000 dishes
frank takes 3000/450 = 6 2/3 hours alone for 1000 dishes
Together they would take (4 *6 2/3)/(4+6 2/3)
= 80/3 *3/32 = 80/32 = 2.5 hours
2007-07-01 23:09:54 · answer #4 · answered by ironduke8159 7 · 0⤊ 0⤋
The 2 1/2 hours is correct together they wash 400 per hour.. so 800 in 2 hours and 200 more in a half an hour and you get 2 and a half hours.... for 1000 dishes
2007-07-01 23:11:23 · answer #5 · answered by James Q 4 · 0⤊ 0⤋
500/2 + 450/3 = dishes in an hour
250 + 150 = 400
1000/400 = time
2.5 hrs
2007-07-02 03:08:04 · answer #6 · answered by BJ 2 · 0⤊ 0⤋
150 minutes
2.5 hours
Find out how many dishes each can wash in the same number of hours. I used 6 hours (360 minutes)
Ben: 120/500=360/x minutes/dishes=minutes/dishes
Ben washes 1500 dishes in 6 hours (360 minutes)
Frank: 180/450=360/x minutes/dishes=minutes/dishes
Frank washes 900 dishes in 6 hours (360 minutes)
They both wash 2400 dishes in 6 hours (360 minutes)
360/2400=x/1000 minutes/dishes=minutes/dishes
x=150
2007-07-01 23:15:00 · answer #7 · answered by Brent F 2 · 0⤊ 0⤋
I believe the answer is 2 hours and 30 minutes. Find Ben's average by dividing 500 by 2. Find Franks average by divinding 450 by 2. Add their averages together. Next divide 1000 bye your answer which should be 400. It gives you 2 and a half hours = 2 hours and 30 minutes. Hope it helps.
2007-07-01 23:04:58 · answer #8 · answered by Anonymous · 0⤊ 0⤋
This is how I would do the problem, off the top of my head and without scrap paper ^^;;
Ben can wash 500 dishes / 2 hrs, which is 250 dishes/hr.
Frank can wash 450 dishes / 3 hrs, which is 150 dishes/hr.
x is the number of hours.
250x + 150x = 1000
400x = 1000
1000/350 = x = 2.5hrs
2007-07-01 23:08:22 · answer #9 · answered by Katie H 1 · 0⤊ 0⤋
Ben and Frank need to go back to school and get an education so they won't have to wash dishes.
2007-07-01 23:11:35 · answer #10 · answered by chilicooker_mkb 5 · 0⤊ 0⤋