Last visit was: 14 Jul 2024, 09:47 It is currently 14 Jul 2024, 09:47
Toolkit
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

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.

# In a population of 100,000 males, 80% can be expected to live to age 6

SORT BY:
Tags:
Show Tags
Hide Tags
Math Expert
Joined: 02 Sep 2009
Posts: 94342
Own Kudos [?]: 640744 [24]
Given Kudos: 85011
CEO
Joined: 26 Feb 2016
Posts: 2865
Own Kudos [?]: 5312 [4]
Given Kudos: 47
Location: India
GPA: 3.12
Director
Joined: 12 Nov 2016
Posts: 569
Own Kudos [?]: 118 [1]
Given Kudos: 167
Location: United States
Schools: Yale '18
GMAT 1: 650 Q43 V37
GRE 1: Q157 V158
GPA: 2.66
Manager
Joined: 03 Apr 2013
Posts: 222
Own Kudos [?]: 249 [0]
Given Kudos: 872
Location: India
Concentration: Marketing, Finance
GMAT 1: 740 Q50 V41
GPA: 3
Re: In a population of 100,000 males, 80% can be expected to live to age 6 [#permalink]
Bunuel wrote:
In a population of 100,000 males, 80% can be expected to live to age 60 and 60% can be expected to live to 80. Given that a male in this group is 60, what is the probability that he lives to 80?

A. 48%
B. 60%
C. 75%
D. 78%
E. 80%

Let me first write down the data given in the question, and for simplicity, I'm assuming tat there are 100 people.

By age 0
Alive = 100

By age 60
Alive = 80

By age 80
Alive = 60

Now, consider the following questions and my understanding

What is the percentage of people who are already 60 will be alive at 80?

In how many ways can we select a person who is 60 years old and will be alive at 80?

$$\frac{60C1}{80C1}$$

75%

Now my understanding of the original question

If a person is randomly selected from people who are 60, what is the probability that he will live to 80?

In this case. we have first already selected a person, now this particular person can be a part of the 60 people who will live to 80, or of the 20 people who will not. We have to calculate the possibility that this particular person is a part of the 60 people who live and not of the 20 people who don't. How do we do that?
I know that I'm getting way too much confused here, but your answer to these questions will really help me understand probability 100%.

Thanks
Manager
Joined: 28 Jun 2015
Posts: 247
Own Kudos [?]: 295 [0]
Given Kudos: 47
Concentration: Finance
GPA: 3.5
Re: In a population of 100,000 males, 80% can be expected to live to age 6 [#permalink]
No. of males that can live to age 60 = 80,000
No. of males that can live to age 80 = 60,000

Probability that a 60-year old male lives to 80 = 60,000/80,000 = 3/4. Ans - C.
RC & DI Moderator
Joined: 02 Aug 2009
Status:Math and DI Expert
Posts: 11470
Own Kudos [?]: 34309 [0]
Given Kudos: 322
Re: In a population of 100,000 males, 80% can be expected to live to age 6 [#permalink]
ShashankDave wrote:
Bunuel wrote:
In a population of 100,000 males, 80% can be expected to live to age 60 and 60% can be expected to live to 80. Given that a male in this group is 60, what is the probability that he lives to 80?

A. 48%
B. 60%
C. 75%
D. 78%
E. 80%

Let me first write down the data given in the question, and for simplicity, I'm assuming tat there are 100 people.

By age 0
Alive = 100

By age 60
Alive = 80

By age 80
Alive = 60

Now, consider the following questions and my understanding

What is the percentage of people who are already 60 will be alive at 80?

In how many ways can we select a person who is 60 years old and will be alive at 80?

$$\frac{60C1}{80C1}$$

75%

Now my understanding of the original question

If a person is randomly selected from people who are 60, what is the probability that he will live to 80?

In this case. we have first already selected a person, now this particular person can be a part of the 60 people who will live to 80, or of the 20 people who will not. We have to calculate the possibility that this particular person is a part of the 60 people who live and not of the 20 people who don't. How do we do that?
I know that I'm getting way too much confused here, but your answer to these questions will really help me understand probability 100%.

Thanks

Hi Shashank,

You have clearly understood the Q correctly even while answering and rewording the Q.
Now you pick up a person A who is part of gang of 80 person reaching 60years.
Now he can get into 60 person who do reach 80 years..
So probability is 60/80..
And this is exactly you have mentioned earlier
Target Test Prep Representative
Joined: 04 Mar 2011
Affiliations: Target Test Prep
Posts: 3037
Own Kudos [?]: 6562 [0]
Given Kudos: 1646
Re: In a population of 100,000 males, 80% can be expected to live to age 6 [#permalink]
Bunuel wrote:
In a population of 100,000 males, 80% can be expected to live to age 60 and 60% can be expected to live to 80. Given that a male in this group is 60, what is the probability that he lives to 80?

A. 48%
B. 60%
C. 75%
D. 78%
E. 80%

Since 80% and 60% are expected to live to ages 60 and 80, respectively, 80,000 and 60,000 males are expected to live to ages 60 and 80, respectively. Thus, the probability that a male lives to age 80, given that he is 60, is:

60,000/80,000 = 3/4 = 75%

Intern
Joined: 21 Mar 2017
Posts: 34
Own Kudos [?]: 13 [0]
Given Kudos: 10
Location: Zimbabwe
Concentration: General Management, Entrepreneurship
GMAT 1: 680 Q45 V38
GMAT 2: 750 Q49 V42
GPA: 3.3
WE:Accounting (Accounting)
Re: In a population of 100,000 males, 80% can be expected to live to age 6 [#permalink]
JeffTargetTestPrep wrote:
Bunuel wrote:
In a population of 100,000 males, 80% can be expected to live to age 60 and 60% can be expected to live to 80. Given that a male in this group is 60, what is the probability that he lives to 80?

A. 48%
B. 60%
C. 75%
D. 78%
E. 80%

Since 80% and 60% are expected to live to ages 60 and 80, respectively, 80,000 and 60,000 males are expected to live to ages 60 and 80, respectively. Thus, the probability that a male lives to age 80, given that he is 60, is:

60,000/80,000 = 3/4 = 75%

what if he wasnt 60. what if he was 30, would the probability change?
Non-Human User
Joined: 09 Sep 2013
Posts: 33966
Own Kudos [?]: 851 [0]
Given Kudos: 0
Re: In a population of 100,000 males, 80% can be expected to live to age 6 [#permalink]
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Re: In a population of 100,000 males, 80% can be expected to live to age 6 [#permalink]
Moderator:
Math Expert
94342 posts