Thought help: If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours…?

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If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours…

?how long will it take for both of them to paint the house together?

This is how my friend did it:
x represent the hours that they will spend

1/4x+1/6x=1
3/12x+2/12x=1
5/12x=1
12*5/12x=1*12
(each side times 12 to get rid of the denominator)
5x=12
x=2.4
2.4 hours=2 hours and 24 minutes

BUT: I don’t understand why I have to add the fractions…its not like she’s going to paint it once and he’s going to paint over it….I thought they’d have to split it (I mean that would make more sense…) It would look like this: .5/x to 1/4 so that sally would only do half of the house …etc. but obviously that didn’t give me the right answer…why?

This open post was written 10 months ago | V/U/S: 621, 15, 4 | Edit Post | Leave a reply | Report Post

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Anonymous edited this post 10 months ago. Read the previous text »

If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours…?

This is how my friend did it: how long will it take for both of them to paint the house together?

x represent the hours that they will spend

1/4x+1/6x=1
3/12x+2/12x=1
5/12x=1
12*5/12x=1*12
(each side times 12 to get rid of the denominator)
5x=12
x=2.4
2.4 hours=2 hours and 24 minutes

BUT: I don’t understand why I have to add the fractions…its not like she’s going to paint it once and he’s going to paint over it….I thought they’d have to split it (I mean that would make more sense…) It would look like this: .5/x to 1/4 so that sally would only do half of the house …etc. but obviously that didn’t give me the right answer…why?

fřëëSöülëd 6 #
An Undisclosed Location | 10 months ago (14 minutes after post)

Ugh! MATH = Mentaly Affected Teachers Harrasing students

Help me with: Happy Song.

Anonymous #
10 months ago (29 minutes after post)

^ well said! ._.

Lano 2 #
An Undisclosed Location | 10 months ago (1 hour, 4 minutes after post)

hmmm. I don’t get it either. I wish I remembered math. I feel like this is something I ought to know. He might be following a generic formula for figuring out how long it takes to do something. hmm. Maybe because its like 1 house per 4 hours. plus 1 house per 6 hours. Nah…that doesn’t sound right. Idk.

Help me with: Happy Birthday.

fřëëSöülëd 6 #
An Undisclosed Location | 10 months ago (1 hour, 8 minutes after post)

I believe they can finish the house in 5 hours. But if John puts down the beer and work at the same pace with Sally, they can finish it in 4.

Help me with: Happy Song.

Lano 2 #
An Undisclosed Location | 10 months ago (1 hour, 9 minutes after post)

FreeSouLed wrote:
I believe they can finish the house in 5 hours. But if John puts down the beer and work at the same pace with Sally, they can finish it in 4.

No, you have to remember, they’re both working at the same time. Sally already works at a pace that will finish the house in four hours. If John helps, they have to be able to finish it in LESS than four hours. 2.4 is the right answer, I just can’t figure out where the fractions and the = 1 comes from.

Help me with: Happy Birthday.

fřëëSöülëd 6 #
An Undisclosed Location | 10 months ago (1 hour, 14 minutes after post)

Lano wrote:

FreeSouLed wrote:
I believe they can finish the house in 5 hours. But if John puts down the beer and work at the same pace with Sally, they can finish it in 4.

No, you have to remember, they’re both working at the same time. Sally already works at a pace that will finish the house in four hours. If John helps, they have to be able to finish it in LESS than four hours. 2.4 is the right answer, I just can’t figure out where the fractions and the = 1 comes from.

Math is sure is complicated. If Sally can finish a house in 4, so if she’s going to do half, it’ll take her 2 hours to finish it? And if you apply the same rule/assumption to John… then 5 is the answer. If John works w/out drinking beer… 4 hours come into play. :) Im sorry. My knowledge about Math is elementary.

Help me with: Happy Song.

Lano 2 #
An Undisclosed Location | 10 months ago (1 hour, 26 minutes after post)

FreeSouLed wrote:

Lano wrote:

FreeSouLed wrote:
I believe they can finish the house in 5 hours. But if John puts down the beer and work at the same pace with Sally, they can finish it in 4.

No, you have to remember, they’re both working at the same time. Sally already works at a pace that will finish the house in four hours. If John helps, they have to be able to finish it in LESS than four hours. 2.4 is the right answer, I just can’t figure out where the fractions and the = 1 comes from.

Math is sure is complicated. If Sally can finish a house in 4, so if she’s going to do half, it’ll take her 2 hours to finish it? And if you apply the same rule/assumption to John… then 5 is the answer. If John works w/out drinking beer… 4 hours come into play. :) Im sorry. My knowledge about Math is elementary.

Hmmm…I didn’t think of it that way. I think the people who wrote the question are assuming they aren’t doing the same amount of work….Not fair to old Sally!

Help me with: Happy Birthday.

casie 4 #
An Unknown Location | 10 months ago (1 hour, 46 minutes after post)

How dare you! >:[ sally isn’t old!

Help me with: I was uninstalling a program on my computer and Microsoft word closed on my essay.

BigWilly! 21 #
An Unknown Location | 10 months ago (2 hours, 3 minutes after post)

It won’t get painted cuz those dirty monkeys are gonna be in the tool-shed all day doing.. what monkeys do.

Help me with: Just had to post this.

roofdonkey 8 #
An Unknown Location | 10 months ago (4 hours, 14 minutes after post)

Heres a simple way to do it in your head:

Sally can paint a house in 4 hours.
Or she paints 1/4 of a house in ONE HOUR.

John can paint a house in 6 hours.
Or he paints 1/6 of a house in ONE HOUR.

Together they can paint ————–> 5/12 of a house in one hour….

OR…
.25 + .167 = .417 in ONE HOUR. How many MORE hours to paint ONE HOUSE?

Now…

To paint ONE HOUSE…
1/.417 = 2.4 hours…

I can do math problems all day long.

(1)

Help me with: This is the serenade I performed for my gf on her birthday.

fřëëSöülëd 6 #
An Undisclosed Location | 10 months ago (4 hours, 20 minutes after post)

roofdonkey wrote:
Heres a simple way to do it in your head:

Sally can paint a house in 4 hours.
Or she paints 1/4 of a house in ONE HOUR.

John can paint a house in 6 hours.
Or he paints 1/6 of a house in ONE HOUR.

Together they can paint ————–> 5/12 of a house in one hour….

OR…
.25 + .167 = .417 in ONE HOUR. How many MORE hours to paint ONE HOUSE?

Now…

To paint ONE HOUSE…
1/.417 = 2.4 hours…

Amazing. I should stop drinking.

I can do math problems all day long.

Help me with: Happy Song.

roofdonkey 8 #
An Unknown Location | 10 months ago (4 hours, 34 minutes after post)

There is always a wiseguy that makes a donkey out of himself, eh?
^^
wiseguy…

Help me with: This is the serenade I performed for my gf on her birthday.

Lano 2 #
An Undisclosed Location | 10 months ago (6 hours, 18 minutes after post)

roofdonkey wrote:
Heres a simple way to do it in your head:

Sally can paint a house in 4 hours.
Or she paints 1/4 of a house in ONE HOUR.

John can paint a house in 6 hours.
Or he paints 1/6 of a house in ONE HOUR.

Together they can paint ————–> 5/12 of a house in one hour….

OR…
.25 + .167 = .417 in ONE HOUR. How many MORE hours to paint ONE HOUSE?

Now…

To paint ONE HOUSE…
1/.417 = 2.4 hours…

I can do math problems all day long.

Thank you. Those fractions and 1 were really bothering me.

Help me with: Happy Birthday.

mythicpaint.co #
An Unknown Location | 6 months, 2 weeks ago (3 months, 2 weeks after post)

Great product. It seems to be a eco-friendly which will surely be good for the environment.
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