marbels

This topic has expert replies
Senior | Next Rank: 100 Posts
Posts: 57
Joined: Mon Nov 17, 2008 7:04 am
Thanked: 1 times

marbels

by DavoodBeater » Thu Jan 08, 2009 2:51 pm
Bag A contains red, white and blue marbles such that the red to white marble ratio is 1:3 and the white to blue marble ratio is 2:3. Bag B contains red and white marbles in the ratio of 1:4. Together, the two bags contain 30 white marbles. How many red marbles could be in bag A?

1
3
4
6
8

OA: [spoiler]6

the number of white marbles in bag B must be multiple of 4 and 30-(white marbles in bag B) must be multiple of 3.[/spoiler]
Source: — Problem Solving |

User avatar
Legendary Member
Posts: 2134
Joined: Mon Oct 20, 2008 11:26 pm
Thanked: 237 times
Followed by:25 members
GMAT Score:730

Re: marbels

by logitech » Thu Jan 08, 2009 3:53 pm
First of all, you should not copy paste the explanation but thanks for the OA.

A

R/W =2/6
W/B = 6/9

B

R/W=1/4

6x+4y=30

6 + 24 and 18 + 12 are the only two options

Since the R/W is 1/3 in A

6/3 = 2 or 18/3=6 are the options
LGTCH
---------------------
"DON'T LET ANYONE STEAL YOUR DREAM!"

Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Thu Jan 08, 2009 6:53 pm
Thanks for the nice problem Davood!

Personaly I dont see why we cant post an explanation. It only adds more value to the post. Its another solution or an approach from may be a different perspective.

M all in for the explanations!!!! :P

Regards,
Cramya

User avatar
Legendary Member
Posts: 2134
Joined: Mon Oct 20, 2008 11:26 pm
Thanked: 237 times
Followed by:25 members
GMAT Score:730

by logitech » Thu Jan 08, 2009 7:41 pm
cramya wrote:Thanks for the nice problem Davood!

Personaly I dont see why we cant post an explanation. It only adds more value to the post. Its another solution or an approach from may be a different perspective.

M all in for the explanations!!!! :P

Regards,
Cramya
Cramya is in the Land of Wonders once again...
LGTCH
---------------------
"DON'T LET ANYONE STEAL YOUR DREAM!"

Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Thu Jan 08, 2009 8:07 pm
Cramya is in the Land of Wonders once again
Whatever that means, hv no clue. Anyways... :lol:

Regards,
CR

User avatar
Legendary Member
Posts: 2134
Joined: Mon Oct 20, 2008 11:26 pm
Thanked: 237 times
Followed by:25 members
GMAT Score:730

by logitech » Thu Jan 08, 2009 8:48 pm
cramya wrote:
Cramya is in the Land of Wonders once again
Whatever that means, hv no clue. Anyways... :lol:

Regards,
CR
Oh you know..Dont play dumb with me! :)
LGTCH
---------------------
"DON'T LET ANYONE STEAL YOUR DREAM!"

Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Thu Jan 08, 2009 9:18 pm
Oh you know..Dont play dumb with me!
U can say it all year long but trust me on this ;I aint got a clue what u have said above, I could seriously care less...

:D

Senior | Next Rank: 100 Posts
Posts: 57
Joined: Mon Nov 17, 2008 7:04 am
Thanked: 1 times

by DavoodBeater » Fri Jan 09, 2009 12:41 am
thanks fiends for your discussions
but i believe that the solution is not needless.
since it gives us one way and i am seeking for other ways, maybe the easier and faster one.
and it 's in spoiler form, so you can skip it easily and post your solutions.
and last, it was not copy paste from the solution logitech :)

Master | Next Rank: 500 Posts
Posts: 113
Joined: Thu Feb 26, 2009 8:13 am
Location: New Jersey
GMAT Score:650

by KICKGMATASS123 » Mon Mar 23, 2009 10:11 pm
guys i understand what is done here..


but it just feels like a leap to the last step..

I find it overwhelming trying to do it in under 2 mins.. Can someone help?

User avatar
Legendary Member
Posts: 682
Joined: Fri Jan 16, 2009 2:40 am
Thanked: 32 times
Followed by:1 members

by Vemuri » Tue Mar 24, 2009 10:20 am
KICKGMATASS123 wrote:guys i understand what is done here..


but it just feels like a leap to the last step..

I find it overwhelming trying to do it in under 2 mins.. Can someone help?
In Bag A: The ratios are given as:

R W B
1 : 3
--- 2 : 3

So, the ratio can otherwise be written as 2:6:9 (Red : White : Blue)

In Bag B: The ratios are given as:

R W
1 : 4

The information provided to us is that together the 2 bags have 30 white balls. To get 30 white balls (based on the ratio), there should be 18 white balls in bag A & 12 white balls in bag B. If 18 (6*3) white balls are in bag A, then there should be 2*3=6 red balls in bag A.

Hope this helps.