Last visit was: 20 Apr 2025, 18:26 It is currently 20 Apr 2025, 18:26
Decision Tracker
My Rewards
New comers' posts
New posts
Unanswered

Close

GRE Prep 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 GRE 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
PREVIOUS TOPIC
NEXT TOPIC

Probability of a couple having a boy child is 0.4. If a couple decides

Tags :
Find Similar Topics  About  Add a Tag

Show Tags
Hide Tags

User avatar
D
Carcass
Verbal Expert
Joined: 18 Apr 2015
Posts: 31603
Own Kudos [?]: 37833 [1]
Given Kudos: 26239
Send PM
Probability of a couple having a boy child is 0.4. If a couple decides [#permalink] New post   21 Aug 2023, 03:49
Expert Reply
1
Bookmarks
00:00

Question Stats:

70% (01:04) correct 30% (00:21) wrong based on 10 sessions

Hide Show timer Statistics

Probability of a couple having a boy child is 0.4. If a couple decides to have 3 children, what is the probability that atleast one of them is a girl child?

A. 0.064
B. 0.36
C. 0.64
D. 0.936
E. 1


Post A Detailed Correct Solution For The Above Questions And Get Kudos.
Question From Our Project: Free GRE Prep Club Tests in Exchange for 20 Kudos

\(\Longrightarrow\) GRE - Quant Daily Topic-wise Challenge
\(\Longrightarrow\) GRE Math Essentials - A most comprehensive handout!!
\(\Longrightarrow\) ALL the GRE Quant and Verbal Practice Directories in ONE place (2023)
\(\Longrightarrow\) Best GRE Test Books of 2023
ShowHide Answer
Official Answer
D
avatar
S
mysterymanrog
Manager
Manager
Joined: 11 Jun 2023
Posts: 77
Own Kudos [?]: 78 [1]
Given Kudos: 14
Send PM
Re: Probability of a couple having a boy child is 0.4. If a couple decides [#permalink] New post   21 Aug 2023, 04:11
1
We are told to find the probability that at least one of the children is a female.

Since these are independent think (similar to the case of a coin flip, heads or tails) we can create two "sets" of events:
P(all boys)+P(at least 1 girl)=1
P(at least 1 girl)=1-p(all boys)
This will shorten the time on the problem considerably - there is only 1 possible combination for all boys rather than the 3 combos for at least 1 girl.

P(all boys)=(2/5)^3=8/125
1-(8/125)=117/125=0.936

Choice D is correct
avatar
S
YB114
Manager
Manager
Joined: 11 Oct 2023
Posts: 69
Own Kudos [?]: 46 [0]
Given Kudos: 25
Send PM
Re: Probability of a couple having a boy child is 0.4. If a couple decides [#permalink] New post   20 Dec 2023, 22:37
if i go with complementary method : 1 - P(BBB) = 1- (0.4×0.4×0.4) = 0.936

but Carcass sir, why cant we find the answer through below approach , what is flaw here ?

P(at least one girl)=P(GBB)+P(GGB)+P(GGG)

= (0.6×0.4×0.4)+(0.6×0.6×0.4)+(0.6×0.6×0.6)

= 0.456
User avatar
D
Carcass
Verbal Expert
Joined: 18 Apr 2015
Posts: 31603
Own Kudos [?]: 37833 [0]
Given Kudos: 26239
Send PM
Probability of a couple having a boy child is 0.4. If a couple decides [#permalink] New post   21 Dec 2023, 02:30
Expert Reply
If you have 3 children and all are boys the probability is 1

If you want at least one girl subtract from 1 the chances to have three boys

You can have GBB,GGB,GGG, BBB

But we are looking for to have at least one girl (last case above)

1-(0.4*0.4*0.4)=1-0.064=0.936

D is the answer
Prep Club for GRE Bot
gmatclubot
Probability of a couple having a boy child is 0.4. If a couple decides [#permalink]
21 Dec 2023, 02:30
Moderators:
adewale223
GRE Instructor
108 posts
bronaugust
GRE Forum Moderator
37 posts
BrushMyQuant
Moderator
1131 posts
VibhuAnurag
GRE Instructor
234 posts

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

Main navigation

Partners

GRE Resources

www.ets.org/gre | About | Terms and Conditions and Privacy Policy | Prep Club for GRE Rules | Contact