If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together?
please show work so i can understand how to do this problem. thanks.
2006-08-29 10:20:32 · 10 answers · asked by Mr. 1 in Science & Mathematics ➔ Mathematics
2 hours.
6hrs-4hrs=2
2006-08-29 10:23:11 · answer #1 · answered by Anonymous · 0⤊ 3⤋
Okay, in one hour sally with have 1/4 of the house done, and John will have 1/6 of it done.
Add 1/4 and 1/6 to get what they can do together:
1/4+1/6=5/12
That means that in 12 hours they will get 5 houses done, but we need to know how many for 1, so set up a proportion:
5/12=1/x where x is the amount of hours to do one house.
5x=12
x=2.4 hours
(Though it seems like averages would would, it can not take 5 hours. Sally can paint a house in 4 hours by her self, having another person to help is not going to slow her down)
2006-08-29 10:36:45 · answer #2 · answered by firefly 3 · 0⤊ 1⤋
Sally paints at the rate of 1/4 house per hour.
John paints at the rate of 1/6 house per hour.
They paint one house. They spend the same amount of time painting (let time = 1)
(1/4)t + (1/6)t = 1
Get a common denominator.
(3/12)t + (2/12)t = 1
(5/12)t = 1
t = 12/5 hours (or 2.4 hours)
sweettea's and DianeD's answer: 5 hours if they paint the house together. 4 hours if Sally paints the house alone. John's help only seems to slow Sally down. John must be a clueless slacker! Or Sally finds him very distracting.
2006-08-29 10:26:23 · answer #3 · answered by Bob G 6 · 1⤊ 1⤋
I was never really that great in word math, however, I enjoy trying, so here goes:
Well, assuming that they split painting the house 50/50.
Sally - 4/2=2 hours to paint half the house.
John - 6/2=3 hours to paint the other half.
It will take them 5 hours to paint the house.
2006-08-29 10:27:46 · answer #4 · answered by DianeD 4 · 1⤊ 1⤋
Sally: 4
John: 6
(4+6)
add them together: 10 hours
divided by 2
10/2 = 5
the average is 5 hours and that's the answer
2006-08-29 10:25:47 · answer #5 · answered by whitesilk 3 · 0⤊ 3⤋
Well, Sally can normally paint the house in 4 hours, but that's if she's not cooking at the same time. She has a bad habit of burning dinner. So if she's cooking, you better add about another hour and a half. Unless they order pizza.
2006-08-29 10:25:54 · answer #6 · answered by Scott B 3 · 1⤊ 2⤋
Sally's work = t/4 , John's work = t/6, where t is hours.
Sally's work + John's work = one house. [This is the important idea to get!]
t/4 + t/6 = 1 then multiply by 12, to get rid of fractions.
3t + 2t = 12
5t = 12
t = 12/5 = 2.4 hours.
2006-08-29 20:29:23 · answer #7 · answered by Polymath 5 · 0⤊ 1⤋
(1/4) + (1/6) =
(10/24)
1/(10/24) =
24/10 = 12/5
ANSWER (I think, but I'm not sure, as the last time I did these kind of problems was in 10th grade): 2.4 hours, which is 2 hours and 24 minutes?
2006-08-29 10:23:30 · answer #8 · answered by rahidz2003 6 · 1⤊ 1⤋
6
4
+___
9 hours
2006-08-29 10:24:49 · answer #9 · answered by BENDER IS THE BOMB!!! (Fav show) 4 · 0⤊ 4⤋
2.4 hours
2006-08-29 10:24:42 · answer #10 · answered by harry d 2 · 1⤊ 1⤋