Last visit was: 18 May 2026, 17:30 It is currently 18 May 2026, 17:30
Home
Messages
Tests
Schools
Events
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
   1   2 
Sub 505 (Easy)|   Probability|            
User avatar
KarishmaB
User avatar
Joined: 16 Oct 2010
Last visit: 18 May 2026
Posts: 16,469
Own Kudos:
79,656
Given Kudos: 485
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,469
Kudos: 79,656
In a certain baord game, a stack of 48 cards, 8 of which 17 Jul 2017, 09:11
Kudos
Add Kudos
Bookmarks
Bookmark this Post
longhaul123
there are total of 48 cards out of which 8 are stock cards so the probability of picking a card from the stock card is 8/48 =S and the other cards are 40/48=N therefore, NNS=5/6*4/5*1/6=1/9 where am i going wrong??
Show more

The probability of picking a Non-stock card, Non-stock card and a Stock card is different from this question.

Here, you are given that the first two are non-stock cards so you do not need to account for the probability of those being non-stock. It is already known that they are.

Also, the probability of selecting NNS would be (40/48)*(39/47)*(8/46)
User avatar
BrentGMATPrepNow
User avatar
Major Poster
Joined: 12 Sep 2015
Last visit: 31 Oct 2025
Posts: 6,733
Own Kudos:
36,593
 [1]
Given Kudos: 799
Location: Canada
Expert
Expert reply
Posts: 6,733
Kudos: 36,593
 [1]
In a certain baord game, a stack of 48 cards, 8 of which 02 Aug 2020, 07:15
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
rajman41
In a certain board game, a stack of 48 cards, 8 of which represent shares of stock, are shuffled and then placed face down. If the first 2 cards selected do not represent shares of stock, what is the probability that the third card selected will represent a share of stock?

A. 1/8
B. 1/6
C. 1/5
D. 3/23
E. 4/23
Show more

GIVEN: Among the 48 cards, 8 cards represent shares of stock.

The first 2 cards selected do NOT represent shares of stock, which means there are 46 cards REMAINING, and 8 of those remaining cards represent shares of stock.

P(the third card selected represents a share of stock) = 8/46 = 4/23

Answer: E

Cheers,
Brent
User avatar
SwethaReddyL
User avatar
Joined: 28 Nov 2023
Last visit: 18 May 2026
Posts: 119
Own Kudos:
26
Given Kudos: 269
Location: India
Products:
GMAT Club Tests
Posts: 119
Kudos: 26
In a certain baord game, a stack of 48 cards, 8 of which 23 Apr 2026, 21:35
Kudos
Add Kudos
Bookmarks
Bookmark this Post
hi KarishmaB
I understand your approach, i have a doubt. The probability of picking the stack card shouldn't be same in any draws? that's why i picked 1/8. Or is that approach applicable only in the replacement questions?
I have seen questions asking what is the probability of getting a head in 100th toss when 150 coins are tossed. The probability will always be 1/2, no matter what the draw is. Am i making sense?

Please respond.

Thanks in advance,
Swetha
KarishmaB


Yes you can. You already know that the first 2 cards are not stock cards. It's like we placed them face up. They anyway are out of the picture. Now we have 46 cards and 8 of them are stock cards. So the probability that the card we pick is a stock card is 8/46 = 4/23.

The probability of picking a stock card keeps increasing as we keep pulling out the non stock cards.
Think: You have 5 cards and 1 of them is the Queen. What is the probability that you will pull out a queen? It's 1/5. What happens after you pull out a non queen? The probability of pulling out a queen now becomes 1/4. It keeps increasing till you reach the last card. If you still haven't pulled out a queen, the last one must be the queen and the probability becomes 1.

Another thing to think about: What happens if you don't know what the first two cards are i.e. what is the probability of picking a share card on the third pick (you don't know what the first two picks are).
Show more
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 18 May 2026
Posts: 110,678
Own Kudos:
815,602
 [1]
Given Kudos: 106,295
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 110,678
Kudos: 815,602
 [1]
In a certain baord game, a stack of 48 cards, 8 of which 23 Apr 2026, 21:50
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
SwethaReddyL
hi KarishmaB
I understand your approach, i have a doubt. The probability of picking the stack card shouldn't be same in any draws? that's why i picked 1/8. Or is that approach applicable only in the replacement questions?
I have seen questions asking what is the probability of getting a head in 100th toss when 150 coins are tossed. The probability will always be 1/2, no matter what the draw is. Am i making sense?

Please respond.

Thanks in advance,
Swetha

Show more

No. The key difference is this: in the coin example, each toss is independent, so the 100th toss still has probability 1/2 for heads. Here, the cards are drawn without replacement, so the probabilities can change from draw to draw depending on what has already been removed.

In this question, we are told that the first 2 cards are not stock cards. That means 2 non-stock cards are gone, so 46 cards remain, and the number of stock cards is still 8. Therefore, the probability that the third card is a stock card is 8/46 = 4/23, not 1/8.
User avatar
KarishmaB
User avatar
Joined: 16 Oct 2010
Last visit: 18 May 2026
Posts: 16,469
Own Kudos:
79,656
Given Kudos: 485
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,469
Kudos: 79,656
In a certain baord game, a stack of 48 cards, 8 of which 23 Apr 2026, 23:20
Kudos
Add Kudos
Bookmarks
Bookmark this Post
... and 1/8 would be the answer if you were putting the card back in the pile and shuffling.

SwethaReddyL
hi KarishmaB
I understand your approach, i have a doubt. The probability of picking the stack card shouldn't be same in any draws? that's why i picked 1/8. Or is that approach applicable only in the replacement questions?
I have seen questions asking what is the probability of getting a head in 100th toss when 150 coins are tossed. The probability will always be 1/2, no matter what the draw is. Am i making sense?

Please respond.

Thanks in advance,
Swetha

Show more
   1   2 
Moderators:
Bunuel
Math Expert
110678 posts
Krunaal
Tuck School Moderator
852 posts