GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 20 Jul 2018, 17:30

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Containers A and B each contain 8 gold coins, 12 silver coins, and not

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Current Student
avatar
B
Joined: 09 May 2017
Posts: 13
WE: Information Technology (Consulting)
Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post Updated on: 29 Jul 2017, 06:22
5
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

60% (01:27) correct 40% (02:06) wrong based on 100 sessions

HideShow timer Statistics

Containers A and B each contain 8 gold coins, 12 silver coins, and nothing else. Container C contains 1 gold coin, 4 silver coins, and nothing else. A container is chosen at random and then a coin is chosen at random from that container. What is the probability that the chosen coin is silver?


A. 4/15

B. 2/5

C. 7/15

D. 3/5

E. 2/3

Originally posted by 3newton on 29 Jul 2017, 01:58.
Last edited by chetan2u on 29 Jul 2017, 06:22, edited 2 times in total.
updated the OA
1 KUDOS received
Current Student
avatar
B
Joined: 09 May 2017
Posts: 13
WE: Information Technology (Consulting)
Re: Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Jul 2017, 02:02
1
Is this approach correct?


(1/3 x 0/8) + (1/3 x 12/20) + (1/3 x 4/5) = 7/15


i.e. Prob of selecting that box X Probability of getting a silver in that box


summation of this for all 3 boxes
1 KUDOS received
Intern
Intern
avatar
B
Joined: 21 Jun 2017
Posts: 10
GMAT 1: 750 Q50 V41
Re: Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Jul 2017, 02:15
1
Does anyone think the question is quite misleading? Containers A and B "each" contains 8 gold coins, 12 silver coins, and nothing else. Does this not indicate that A contains 8G and 12S and that B contains the same coins as A? Only after I finish my calculation that I realized this way was wrong.
Manager
Manager
avatar
B
Joined: 02 Nov 2015
Posts: 170
GMAT 1: 640 Q49 V29
Premium Member
Re: Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Jul 2017, 02:38
3newton wrote:
Is this approach correct?


(1/3 x 0/8) + (1/3 x 12/20) + (1/3 x 4/5) = 7/15


i.e. Prob of selecting that box X Probability of getting a silver in that box


summation of this for all 3 boxes

Hey 3newton,
Can you please tell why you have multiplied 0/3. Rest of he things are clear.
Tanks in advance.

Sent from my Lenovo TAB S8-50LC using GMAT Club Forum mobile app
Manager
Manager
avatar
B
Joined: 02 Nov 2015
Posts: 170
GMAT 1: 640 Q49 V29
Premium Member
Re: Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Jul 2017, 02:39
Rather I would have gone for 1/3(12/20+12/20+4/5).
Thus would have led to 2/3.
Ans E.

Please correct my understanding of needed.

Sent from my Lenovo TAB S8-50LC using GMAT Club Forum mobile app
Intern
Intern
avatar
B
Joined: 06 Sep 2013
Posts: 34
Location: India
Concentration: Leadership, Strategy
Schools: ISB '19 (A)
GMAT 1: 770 Q50 V44
GPA: 3.7
WE: Information Technology (Consulting)
Re: Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Jul 2017, 06:06
kumarparitosh123 wrote:
Rather I would have gone for 1/3(12/20+12/20+4/5).
Thus would have led to 2/3.
Ans E.

Please correct my understanding of needed.

Sent from my Lenovo TAB S8-50LC using GMAT Club Forum mobile app


The line "Containers A and B each contain 8 gold coins, 12 silver coins, and nothing else" is quite misleading here.
What it actually wants to say is that Container A contains 8 Gold coins and nothing else, and Container B contains 12 Silver coins and nothing else.

Seems to be a poor quality question..
Expert Post
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 6258
Re: Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Jul 2017, 06:21
3newton wrote:
Containers A and B each contain 8 gold coins, 12 silver coins, and nothing else. Container C contains 1 gold coin, 4 silver coins, and nothing else. A container is chosen at random and then a coin is chosen at random from that container. What is the probability that the chosen coin is silver?


A. 4/15

B. 2/5

C. 7/15

D. 3/5

E. 2/3



Hi...
the way Q is written, answer is clearly E.....

Q means BOTH A and B contain 8G and 12S. container C contains 1G and 4S..

Now how have you interpreted it as 0 silver in A is wrong...

Any of three can be choosen, so choosing each means probability of 1/3..

total \(\frac{1}{3}*\frac{12}{20}*2+\frac{1}{3}*\frac{4}{5} = \frac{2}{3}\)

E
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

1 KUDOS received
SC Moderator
avatar
D
Joined: 22 May 2016
Posts: 1832
Premium Member CAT Tests
Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Jul 2017, 06:22
1
3newton wrote
Quote:
Containers A and B each contain 8 gold coins, 12 silver coins, and nothing else. Container C contains 1 gold coin, 4 silver coins, and nothing else. A container is chosen at random and then a coin is chosen at random from that container. What is the probability that the chosen coin is silver?

A. 4/15

B. 2/5

C. 7/15

D. 3/5

E. 2/3

K_Leon wrote:
Does anyone think the question is quite misleading? Containers A and B "each" contains 8 gold coins, 12 silver coins, and nothing else. Does this not indicate that A contains 8G and 12S and that B contains the same coins as A? Only after I finish my calculation that I realized this way was wrong.

Yes. I remain confused. I got the correct answer through no fault of my own. I guessed.

A thorough discussion of "each" and "both" belongs in SC, so I'll keep it as short as I can. One hat I wear is editor of English prose.

"Each" refers to every one of any number, when considered individually or separately. "Both" refers to two, taken together. "Each," almost always, is a singular subject (hence singular verb). "Both" is a plural subject. The prompt's plural verb "contain" implies both. ????

"Each" should be used to emphasize the individuality of separate conditions. "The company gave both women $100,000." Unclear. Corrected: "The company gave each woman $100,000." (The women did not split the $100,000.)

Clarity would be simple to achieve. "Jars A and B both contain ..." Or "Jars A and B contain, respectively, 8 gold and 12 silver coins."

I still can't figure out how, in 3newton 's response, A has 0 silver coins of 8 total but B has 12 silver coins of 20 total. Doesn't A also have 20 coins?

If A = 8 total and B = 12 total, I think the equation is (1/3 * 0/8) + (1/3 * 12/12) + (1/3 * 4/5) = 3/5

kumarparitosh123 , I think you are correct.

If A and B both have 8 gold and 12 silver coins, I agree that the equation is (1/3 * 12/20) + (1/3 * 12/20) + (1/3 * 4/5) = 2/3

That said, if words were clear and OA were different, the content would be interesting. 3newton , are you sure the OA is correct?

chetan2u , I disagree respectfully. I don't think there's anything clear about it. Both answers D and E are defensible.
_________________

In the depths of winter, I finally learned
that within me there lay an invincible summer.

-- Albert Camus, "Return to Tipasa"

Expert Post
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 6258
Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Jul 2017, 06:33
genxer123 wrote:
3newton wrote
Quote:
Containers A and B each contain 8 gold coins, 12 silver coins, and nothing else. Container C contains 1 gold coin, 4 silver coins, and nothing else. A container is chosen at random and then a coin is chosen at random from that container. What is the probability that the chosen coin is silver?

A. 4/15

B. 2/5

C. 7/15

D. 3/5

E. 2/3

K_Leon wrote:
Does anyone think the question is quite misleading? Containers A and B "each" contains 8 gold coins, 12 silver coins, and nothing else. Does this not indicate that A contains 8G and 12S and that B contains the same coins as A? Only after I finish my calculation that I realized this way was wrong.

Yes. I remain confused. I got the correct answer through no fault of my own. I guessed.

A thorough discussion of "each" and "both" belongs in SC, so I'll keep it as short as I can. One hat I wear is editor of English prose.

"Each" refers to every one of any number, when considered individually or separately. "Both" refers to two, taken together. "Each," almost always, is a singular subject (hence singular verb). "Both" is a plural subject. The prompt's plural verb "contain" implies both. ????

"Each" should be used to emphasize the individuality of separate conditions. "The company gave both women $100,000." Unclear. Corrected: "The company gave each woman $100,000." (The women did not split the $100,000.)

Clarity would be simple to achieve. "Jars A and B both contain ..." Or "Jars A and B contain, respectively, 8 gold and 12 silver coins."

I still can't figure out how, in 3newton 's response, A has 0 silver coins of 8 total but B has 12 silver coins of 20 total. Doesn't A also have 20 coins?

If A = 8 total and B = 12 total, I think the equation is (1/3 * 0/8) + (1/3 * 12/12) + (1/3 * 4/5) = 3/5

kumarparitosh123 , I think you are correct.

If A and B both have 8 gold and 12 silver coins, I agree that the equation is (1/3 * 12/20) + (1/3 * 12/20) + (1/3 * 4/5) = 2/3

That said, if words were clear and OA were different, the content would be interesting. 3newton , are you sure the OA is correct?

chetan2u ,I disagree respectfully. I don't think there's anything clear about it. Both answers D and E are defensible.


Hi,

Disagreement is always good, and with respect is even better :wink: .
So I may agree with what you have written but not with D as answer in any way, neither mathematically or grammatically..

an error of contain/contains is perfectly fine in the forum, may not be in actuals. but there too it would mean the same.

say if I take what you say --
Quote:
Containers A and B each contain 8 gold coins, 12 silver coins, and nothing else. could mean the equation is (1/3 * 0/8) + (1/3 * 12/12) + (1/3 * 4/5) = 3/5

so A has 8 gold coins , B has 12 silver BUT WHO has " nothing else"
so this solution does not stand grammatically too..
E is the only possible answer.
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

SC Moderator
avatar
D
Joined: 22 May 2016
Posts: 1832
Premium Member CAT Tests
Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Jul 2017, 08:21
chetan2u wrote:
genxer123 wrote:

chetan2u ,I disagree respectfully. I don't think there's anything clear about it. Both answers D and E are defensible.


Hi,

Disagreement is always good, and with respect is even better :wink: .
So I may agree with what you have written but not with D as answer in any way, neither mathematically or grammatically..

an error of contain/contains is perfectly fine in the forum, may not be in actuals. but there too it would mean the same.

say if I take what you say --
Quote:
Containers A and B each contain 8 gold coins, 12 silver coins, and nothing else. could mean the equation is (1/3 * 0/8) + (1/3 * 12/12) + (1/3 * 4/5) = 3/5

so A has 8 gold coins , B has 12 silver BUT WHO has " nothing else"
so this solution does not stand grammatically too..
E is the only possible answer.


"A has 8 gold coins, B has 12 silver coins, and [in each there is] nothing else."

That's correct, grammatically.
_________________

In the depths of winter, I finally learned
that within me there lay an invincible summer.

-- Albert Camus, "Return to Tipasa"

Senior Manager
Senior Manager
avatar
S
Joined: 15 Jan 2017
Posts: 361
CAT Tests
Re: Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Aug 2017, 00:20
I did a more 'one at a time' probability and added them up:
--> prob of container: 1/3 (choosing one out of 3 containers A,B,C)
--> prob of silver per container --> if either A and B --> then 1/12
--> if either C --> then 1/4
Prob of all silver --> 1/4 + 1/16 = 1/3
--> Prob of silver and container =1/3 + 1/3 -->2/3 (E)
1 KUDOS received
Senior Manager
Senior Manager
avatar
S
Joined: 15 Jan 2017
Posts: 361
CAT Tests
Re: Containers A and B each contain 8 gold coins, 12 silver coins, and not  [#permalink]

Show Tags

New post 29 Aug 2017, 00:24
1
Also, I do notice an error in phrasing 'each contain' -- since I read container A and B; it skipped my attention. (this is not advisable anyway in GMAT exam where every word is important) . Now it would complicate matters because it means A and B total would be 16 gold and 24 silver coins --> I think this question needs to be re-phrased :)
Re: Containers A and B each contain 8 gold coins, 12 silver coins, and not &nbs [#permalink] 29 Aug 2017, 00:24
Display posts from previous: Sort by

Containers A and B each contain 8 gold coins, 12 silver coins, and not

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  

Events & Promotions

PREV
NEXT


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.