Last visit was: 18 May 2025, 02:37 It is currently 18 May 2025, 02:37
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
User avatar
devarpanc
Joined: 11 Aug 2024
Last visit: 12 May 2025
Posts: 5
Given Kudos: 5
Location: South Africa
Posts: 5
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 18 May 2025
Posts: 101,490
Own Kudos:
725,100
 [1]
Given Kudos: 93,534
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 101,490
Kudos: 725,100
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
spvdrrooo
Joined: 20 Aug 2024
Last visit: 08 Mar 2025
Posts: 1
Given Kudos: 8
Location: Belgium
Posts: 1
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
devarpanc
Joined: 11 Aug 2024
Last visit: 12 May 2025
Posts: 5
Given Kudos: 5
Location: South Africa
Posts: 5
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Off course, Noob mistake. Thank you.
Bunuel
devarpanc
Bunuel
Official Solution:


If event \(A\) and event \(B\) are independent, is the probability that both event \(A\) and event \(B\) occur greater than 0.3?

Notice that since events \(A\) and \(B\) are independent, then the probability that both occur, equals to the product of their individual probabilities, so \(P(A \text { and } B)=P(A)*P(B)\). Also notice that \(0 \le P(A) \le 1\) and \(0 \le P(B) \le1\).

(1) Probability that \(A\) will occur is 0.25.

Since \(P(A)=0.25\), then \(P(A \text { and } B)=P(A)*P(B) \le 0.25 \lt 0.3\). Sufficient.

Or consider the following: how can the probability that both Event \(A\) and Event \(B\) will happen be more than individual probability of each happening? So, the probability that both happen cannot be more than 0.25.

(2) Probability that B will NOT occur is 0.71.

The same here: since \(P(B)=1-0.71=0.29\), then \(P(A \text { and } B)=P(A)*P(B) \le 0.29 \lt 0.3\). Sufficient.


Answer: D

Hi Guys my probability concepts are still weak so if someone can please help me:

1- P(A) = 0.25, what if the probability of P(B)= 0.2, then P (A and B) = 0.25 x 0.2 = 0.5 > 0.3. What if P(B) = 0.1

then P (A and B) = 0.25 x 0.1 = 0.025 < 0.3@

Thank you

Bunuel

0.25 x 0.2 = 0.05, NOT 0.5.

Hope this helps.
User avatar
RishiAgarwal231
Joined: 31 Aug 2024
Last visit: 16 Mar 2025
Posts: 8
Own Kudos:
Given Kudos: 3
Posts: 8
Kudos: 2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
How to do quickly:

we know that for independent events p(A)*p(B) is p(A and B)

1) if A = 0.25, to make this greater than 0.3, B has to be greater than 1 which is not possible since Probability is always less than equal to 1
CONFIRMED NO, statement 1 is sufficient

2) Similarly, if B' = 0.71, B=1-0.71 = 0.29; to make A*B > 0.3, A has to be greater than one. Again, Probability is always less than equal to 1
CONFIRMED NO, statement 2 is sufficient


Answer: D

Bunuel
If event \(A\) and event \(B\) are independent, is the probability that both event \(A\) and event \(B\) occur greater than 0.3?


(1) Probability that \(A\) will occur is 0.25

(2) Probability that \(B\) will NOT occur is 0.71
User avatar
Dbrunik
Joined: 13 Apr 2024
Last visit: 16 Feb 2025
Posts: 279
Own Kudos:
Given Kudos: 267
Location: United States (MN)
Concentration: Finance, Technology
GMAT Focus 1: 625 Q84 V82 DI77
GMAT Focus 1: 625 Q84 V82 DI77
Posts: 279
Kudos: 98
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I think this is a high-quality question and I agree with explanation.
User avatar
idlch
Joined: 23 Jun 2023
Last visit: 06 May 2025
Posts: 6
Given Kudos: 9
Location: India
Posts: 6
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I like the solution - it’s helpful.
   1   2 
Moderators:
Math Expert
101490 posts
Founder
40671 posts