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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Probability of a couple having a boy child is 0.4.
[#permalink]
09 Jul 2019, 03:13
09 Jul 2019, 03:13
00:00
Question Stats:
80% (01:17) correct
19% (00:27) wrong based on 21 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 at least one of them is a girl child?
A) 0.064
B) 0.64
C) 0.36
D) 0.936
E) 1
Source : GRE 1 Green book from Jamboree
A) 0.064
B) 0.64
C) 0.36
D) 0.936
E) 1
Source : GRE 1 Green book from Jamboree
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: Probability of a couple having a boy child is 0.4.
[#permalink]
09 Jul 2019, 05:22
09 Jul 2019, 05:22
2
Bijesh wrote:
Probability of a couple having a boy child is 0.4. If a couple decides to have 3 children, what is the probability that at least one of them is a girl child?
A) 0.064
B) 0.64
C) 0.36
D) 0.936
E) 1
A) 0.064
B) 0.64
C) 0.36
D) 0.936
E) 1
We want P(select at least 1 girl)
When it comes to probability questions involving "at least," it's best to try using the complement.
That is, P(Event A happening) = 1 - P(Event A not happening)
So, here we get: P(getting at least 1 girl) = 1 - P(not getting at least 1 girl)
What does it mean to not get at least 1 girl? It means getting zero girls.
So, we can write: P(getting at least 1 girl) = 1 - P(getting zero girls)
P(getting zero girls)
P(getting zero girls) = P(getting 3 boys)
= P(1st child is boy AND 2nd child is boy AND 3rd child is boy)
= P(1st child is boy) x P(2nd child is boy) x P(3rd child is boy)
= 0.4 x 0.4 x 0.4
= 0.064
So, P(getting at least 1 girl) = 1 - 0.064
= 0.936
Answer: D
Cheers,
Brent
Re: Probability of a couple having a boy child is 0.4.
[#permalink]
09 Jul 2019, 06:54
09 Jul 2019, 06:54
Thank you Sir. This approach made it look very easy.
