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.
Senior Manager
Joined: 23 Jan 2021
Posts: 294
Given Kudos: 81
Concentration: , International Business
20 boys and 40 girls are in Group A, while at least 7 boys, together w
[#permalink]
27 Jun 2021, 07:55
27 Jun 2021, 07:55
2
00:00
Question Stats:
60% (02:38) correct
39% (02:55) wrong based on 23 sessions
Hide Show timer Statistics
20 boys and 40 girls are in Group A, while at least 7 boys, together with some girls are in Group B. To choose one person from each of the group, the probability that both are boys is no greater than 1/15. Which of the following statements must be true?
Indicate all such statements.
A. The number of people in group B is greater than 34.
B. The number of girls in group B is greater than 32.
C. The number of girl in group B is less than 34.
Post a detailed solution and get a kudos!
Indicate all such statements.
A. The number of people in group B is greater than 34.
B. The number of girls in group B is greater than 32.
C. The number of girl in group B is less than 34.
Post a detailed solution and get a kudos!
Re: 20 boys and 40 girls are in Group A, while at least 7 boys, together w
[#permalink]
28 Jun 2021, 00:17
28 Jun 2021, 00:17
3
For group A the probability of picking one boy is 20/60= 1/3
So, the probability of picking one boy from group B will at least 1/5 ( hence, 1/5 * 1/3 = 1/15)
group B has at least 7 boys. So group B must have at least 5*7= 35 person total
So, option A must be true.
option B is false for total 35 person, though it can be true if total person in increased. As it's partially true, we can't take it.
Same goes for option C
So, answer is "A"
Kudos!!!
So, the probability of picking one boy from group B will at least 1/5 ( hence, 1/5 * 1/3 = 1/15)
group B has at least 7 boys. So group B must have at least 5*7= 35 person total
So, option A must be true.
option B is false for total 35 person, though it can be true if total person in increased. As it's partially true, we can't take it.
Same goes for option C
So, answer is "A"
Kudos!!!
20 boys and 40 girls are in Group A, while at least 7 boys, together w
[#permalink]
28 Jun 2021, 01:46
28 Jun 2021, 01:46
2
Lets presume x number of girls (at least) in group B
Now, Probability of picking 1 boy from
Group A= 20/60=1/3
Group B= 7/(x+7)
So, Probabilitt of picking 2 boy from group A & B is
1/3×7/(x+7)=1/15
=> 7/(3x+21)=1/15
=> 3x+21=105
=> x=28
That means in group B the number of girls is 28 or higher.
So, the number of people in group B is (28+7)=35 or more.
Statement A:True.
Statement B:False; Girls# in B can be less than 32
Statement C:False; Girls# in B can be higher than 34
Posted from my mobile device
Now, Probability of picking 1 boy from
Group A= 20/60=1/3
Group B= 7/(x+7)
So, Probabilitt of picking 2 boy from group A & B is
1/3×7/(x+7)=1/15
=> 7/(3x+21)=1/15
=> 3x+21=105
=> x=28
That means in group B the number of girls is 28 or higher.
So, the number of people in group B is (28+7)=35 or more.
Statement A:True.
Statement B:False; Girls# in B can be less than 32
Statement C:False; Girls# in B can be higher than 34
Posted from my mobile device
