Yes I know

[Zysoclaplem]

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.

I know the answer, but need the formula.

 

[Sheepathon]

5?

 

[KLin]

add the time together and divide by 2.

 

[NiKeFiDO]

eeerrr.....

 

[NiKeFiDO]

Originally posted by: KLin
add the time together and divide by 2.

but they work at different rates, that doesnt work out.

choose answer (E) not enough info

 

[HardcoreRobot]

is it x/4 + x/6 = 1 ?

 

[leftyman]

why dont you side your house instead?

 

[KLin]

Originally posted by: NiKeFiDO

Originally posted by: KLin
add the time together and divide by 2.

but they work at different rates, that doesnt work out.

choose answer (E) not enough info

Well damnit, the answer is 42 then.

 

[Trygve]

1/(1/a + 1/b) = 2.4 hours

 

[meltdown75]

i predict 8 hours.

Sally won't shut the hell up and let John paint it the way he wants to. he's "not doing it right."

 

[Zysoclaplem]

The answer is 2 hours and 24 minutes. Or 144 minutes. But I don't know the formula.

 

[imported_Dimicron]

Originally posted by: leftyman
why dont you side your house instead?

"Hi, I'm Bob Vela... Today we're going to talk about tough, new, Sears aluminum siding..."

 

[KLin]

In 1 hr Sally can paint 1/4
John can paint 1/6 in 1hr.
Combined, they will paint in 1/4 + 1/6
Taking LCM
6+4/24 = 10/24 = 5/12
Therefore total time they will take is 12/5 = 2hrs + 2/5x60 mins = 2hr 24 mins

shamelessly stolen from another site

 

[BigJ]

Originally posted by: meltdown75
i predict 8 hours.

Sally won't shut the hell up and let John paint it the way he wants to. he's "not doing it right."

Bingo!

 

[HardcoreRobot]

look at my post above

 

[DougK62]

Originally posted by: KLin
add the time together and divide by 2.

I hope you're jost joking. lol

 

[KLin]

Originally posted by: DougK62

Originally posted by: KLin
add the time together and divide by 2.

I hope you're jost joking. lol

I wasn't. I'm a moron too

 

[Legend]

Originally posted by: meltdown75
i predict 8 hours.

Sally won't shut the hell up and let John paint it the way he wants to. he's "not doing it right."

 

[dquan97]

my work:
x=time in hrs
y=# of house

1/4x=y : sally
1/6x=y : john
combine the two into 1/4x + 1/6x=y
take the LCM > 6/24x + 4/24x = y
combine into > 10/24x=y
multiply both sides by 24/10, so y=24/10 or 2.4hrs = 2hrs 24mins

OP, you can paypal me for the work later

 

[shimsham]

is sally hot? how much time will john waste checking her out?

pics?

 

[tikwanleap]

Originally posted by: dquan97
my work:
x=time in hrs
y=# of house

1/4x=y : sally
1/6x=y : john
combine the two into 1/4x + 1/6x=y
take the LCM > 6/24x + 4/24x = y
combine into > 10/24x=y
multiply both sides by 24/10, so y=24/10 or 2.4hrs = 2hrs 24mins

OP, you can paypal me for the work later

Originally posted by: shimsham
is sally hot? how much time will john waste checking her out?

pics?

Both quoted for truth!

 

[Zysoclaplem]

Thanks everyone. Several of you got it correct, just in different ways. I appreciate the help. Muah!

 

[marvdmartian]

My memory's not what it used to be (too much internet pron, ya know? ), but the way I figured it out was like this:

Sally can paint the house in 4 hours, or do 1/4 of the house in one hour.
John can pain the house in 6 hours, or do 1/6 of the house in one hour.

Break it down to lowest common denominator:
Sally = 1/4, or 3/12 John = 1/6, or 2/12
Now add them up, and you find out how much of the house gets painted each hour, 5/12.

Then it's a simple algebra equation:
1/5=x/12, or 5x=12, or x=2.4hours it will take them to paint the house.

The simple way to check an equation like that is to figure out that in 2.4 hours, Sally will have painted 7.2/12 of the house (3/12 x 2.4), and John will have painted 4.8/12 (2/12 x 2.4), for a grand total of 7.2 + 4.8/12, or 12/12.....the entire house!

And yes, my brain often works in convoluted ways like this!! LOL