[samwoo2go]

Originally Posted by NycE93M3

my sister is doing a practice test and she had this question

but i dont understand how to go about starting

2. 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?

The answer is 4 hours and 15 minutes

Sally will paint the fucking house by herself for 4 hours and taking a 15 minutes break in between to make John a god damn sandwich while John watch football and chill back with a bud after a long ass week of hard work, during which Sally didn't do shit except spending John's money. Sally is a dumb hoe

[py335]

oh god reading this problem is bringing back those god awful flashbacks of non-stop SAT studying since like freaking 6th grade (indian parents). the answer is A. though samwoo was VERYYY close i must say

[Baoer]

this looks a lot like a gmat question

[hks786]

Originally Posted by NycE93M3

did u cheat?????

cuz i posted the answer already aswell check the link in my 3rd or 4th post

lol just noticed that. No I didnt cheat. It's not a hard problem to solve. The way to think of it is even though John is slower (Sally is 50% faster) he will still cover areas whilst Sally is working. First you need to work out how much they would both cover in 1 hour. You can use fractions and do equations. After that its easy.

[brocken]

Makes me so glad I don't have to do math like that anymore...As soon as I was out of calculus all of that stuff started falling out of my brain.
The only thing I remember/use anymore besides basic addition/mult is geometry/trig for household projects (or building speakers).

[hks786]

Originally Posted by BMW E90

But at the same time you could argue that because John can paint the house "by himself" in 6 hours, with the help of Sally he can do it faster, thus the 5 hours. She helps reduce his time while he drags her down. Since the answers weren't provided there was no way of knowing what kind of math was involved. It could have been as simple as averaging or as "complex" as what the OP posted.

No really it is simple. You dont even need to think of it as a maths problem until you start doing the calculations. To get your head around it read my previous post.

[klipseracer]

Originally Posted by NycE93M3

^and i can do it in 2,

someone solve, how long it will take us to do it together?

1.5? HAHAHHAHH

[radix]

Originally Posted by BMW E90

But at the same time you could argue that because John can paint the house "by himself" in 6 hours, with the help of Sally he can do it faster, thus the 5 hours. She helps reduce his time while he drags her down. Since the answers weren't provided there was no way of knowing what kind of math was involved. It could have been as simple as averaging or as "complex" as what the OP posted.

The problem with the 5 hour answer is twofold:

1. It assumes they each paint exactly 1/2 of the house.

2. It assumes that they do so sequentially, as opposed to in parallel.

If they both paint exactly one half of the house in parallel, the time taken to complete the task will be the greater of their two respective times, in this case three hours, as she would finish her half in 2 hours, and he would finish his half in three. Clearly since she paints at a faster rate than he, she would accomplish more in one hour than he would, thus you have the equation hks786 presented.

[Nedim]

Originally Posted by TK-421

You would think the answer would've been found pretty quickly with all the Asians on the forum.

HAHAHAHA

I hate math..
(I'm not Asian)

[MontegoGoGoGo]

Originally Posted by ak335

fawk math

+ 2 x 1,000,000

[vasaline]

Originally Posted by hks786

In 1 hour Sally will paint 1/4 and John will paint 1/6.
Therefore in 1 hour they will paint:

1/4 + 1/6
= 6/24 + 4/24
= 10/24
= 5/12

Therefore in 2 hours they will paint 10/12 of the house. For the last 2/12:

For 5/12 it takes 1 hour so for 2/12 we are looking at 2/5 of an hour which is 24 mins. So in total 2 hours and 24 mins.

So there is 2/12 left but how did u end up getting 2/5 to get 24 mins?

[radix]

Originally Posted by vasaline

So there is 2/12 left but how did u end up getting 2/5 to get 24 mins?

5 / 12 = 2.4 (or 2 + 2/5)

60 / 5 = 12

12 * 2 = 24

[vasaline]

Thanks for the clarification... Haven't seen these problems since high school...

[ToothDoc]

These questions need a quick solution... if there were two people who can do it in 4 hours, it would be done in 2 hours. If there are two people who can do it in 6 hours, it would be done in 3 hours. So the only answer that is in between 2 and 3 hours is A. Sometimes the fastest solution isn't figuring it out algebraically. If you solved every math problem in the traditional way, you'll never have time to get perfect scores on those timed math tests (like the SAT).

[Aija]

haha for some reason i like these type of questions.....the one i like is

(X-A)*(X-B)*(X-C)........(X-Z) =

What does this equal to? Fairly easy question~

[BMW F22]

Originally Posted by hks786

No really it is simple. You dont even need to think of it as a maths problem until you start doing the calculations. To get your head around it read my previous post.

Originally Posted by radix

The problem with the 5 hour answer is twofold:

1. It assumes they each paint exactly 1/2 of the house.

2. It assumes that they do so sequentially, as opposed to in parallel.

If they both paint exactly one half of the house in parallel, the time taken to complete the task will be the greater of their two respective times, in this case three hours, as she would finish her half in 2 hours, and he would finish his half in three. Clearly since she paints at a faster rate than he, she would accomplish more in one hour than he would, thus you have the equation hks786 presented.

Yup. Without reading the answers I just assumed things and thus said 5 hours. I love how so many people (not saying you guys) came out and said "oh yeah it should be this and that" AFTER the OP posted the answers.

[08rookie]

what if sally and john had access to an Dupont 553 ultra-sinc paint sprayer that completes a 4 hr job in 15 minutes

[08rookie]

Originally Posted by 08rookie

what if sally and john had access to an Dupont 553 ultra-sinc paint sprayer that completes a 4 hr job in 15 minutes

what a jerk off

[samwoo2go]

Originally Posted by ToothDoc

These questions need a quick solution... if there were two people who can do it in 4 hours, it would be done in 2 hours. If there are two people who can do it in 6 hours, it would be done in 3 hours. So the only answer that is in between 2 and 3 hours is A. Sometimes the fastest solution isn't figuring it out algebraically. If you solved every math problem in the traditional way, you'll never have time to get perfect scores on those timed math tests (like the SAT).

ding ding ding. This problem was meant to be solved in under 15 seconds, since the answer has to be between 2 and 3 hours (and only 1 answer falls in that category). This is why some really smart people suck at testing and some people just excel at standardized tests. This is actually 1 of the most basic techniques taught in my SAT prep class back in the day.

[TK-421]

Originally Posted by 08rookie

what a jerk off

Did you really just quote... and insult yourself?

[08rookie]

Originally Posted by TK-421

Did you really just quote... and insult yourself?

yes. i was intoxicated last night. i apologize.

[pmeloche]

The time is actually a little longer than 2.4 hours because you have to account for the time that Sally took to make John a sandwich.