GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 21 Feb 2019, 14:33

### 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

## Events & Promotions

###### Events & Promotions in February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar

February 21, 2019

February 21, 2019

10:00 PM PST

11:00 PM PST

Kick off your 2019 GMAT prep with a free 7-day boot camp that includes free online lessons, webinars, and a full GMAT course access. Limited for the first 99 registrants! Feb. 21st until the 27th.
• ### Free GMAT RC Webinar

February 23, 2019

February 23, 2019

07:00 AM PST

09:00 AM PST

Learn reading strategies that can help even non-voracious reader to master GMAT RC. Saturday, February 23rd at 7 AM PT

# If a family has three children, what is the probability that the famil

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 53063
If a family has three children, what is the probability that the famil  [#permalink]

### Show Tags

25 May 2018, 03:24
1
5
00:00

Difficulty:

15% (low)

Question Stats:

77% (00:55) correct 23% (01:34) wrong based on 110 sessions

### HideShow timer Statistics

If a family has three children, what is the probability that the family has at least one girl?

A. 1

B. 0.875

C. 0.75

D. 0.50

E. 0.375

_________________
Manager
Joined: 30 May 2017
Posts: 135
Location: United States
Schools: HBS '21
GMAT 1: 690 Q50 V32
GRE 1: Q168 V164
GPA: 3.57
Re: If a family has three children, what is the probability that the famil  [#permalink]

### Show Tags

25 May 2018, 04:03
Bunuel wrote:
If a family has three children, what is the probability that the family has at least one girl?

A. 1

B. 0.875

C. 0.75

D. 0.50

E. 0.375

The probability that all three children are boys is 0.5*0.5*0.5 = 0.125

The probability that the family has at least one girl is 1-0.125 = 0.875

Hence Option B = 0.875 is the answer.
_________________

Kindly press the +1Kudos if you like the explanation. Thanks a lot!!!

Manager
Joined: 02 Jul 2017
Posts: 55
Re: If a family has three children, what is the probability that the famil  [#permalink]

### Show Tags

25 May 2018, 04:44
Probability of having at least one girl =1- Prob of all boys
Prob of having all boys =0.5*0.5*0.5
Manager
Joined: 07 Apr 2018
Posts: 105
Re: If a family has three children, what is the probability that the famil  [#permalink]

### Show Tags

26 May 2018, 06:01
Probability of having atleast a girl= 1- Probability of having all boys

Probability of having a boy= 1/2
Probability of having three boys= (1/2)(1/2)(1/2) = 1/8

Probability of having atleast a girl = 1- (1/8) = 7/8 = 0.875

_________________

Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 4944
Location: United States (CA)
Re: If a family has three children, what is the probability that the famil  [#permalink]

### Show Tags

29 May 2018, 08:16
1
Bunuel wrote:
If a family has three children, what is the probability that the family has at least one girl?

A. 1

B. 0.875

C. 0.75

D. 0.50

E. 0.375

The two events “at least one girl” and “no girls” are complementary events, which means that the sum of their probabilities is 1. Thus, we have:

P(at least 1 girl) = 1 - P(no girls)

P(no girls) = 1/2 x 1/2 x 1/2 = ⅛

So, P(at least 1 girl) = 1 - P(no girls) = 1 - 1/8 = 7/8 = 0.875.

_________________

Scott Woodbury-Stewart
Founder and CEO

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Manager
Joined: 31 Jan 2018
Posts: 69
Re: If a family has three children, what is the probability that the famil  [#permalink]

### Show Tags

29 May 2018, 12:24
Bunuel wrote:
If a family has three children, what is the probability that the family has at least one girl?

A. 1

B. 0.875

C. 0.75

D. 0.50

E. 0.375

Total sample space = BBB,BBG,BGB,GBB,GGB,GBG,BGG,GGG where G=Girl and B=BOY

probability that at least one of the children will be girl = 7/8 = .875
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 4944
Location: United States (CA)
Re: If a family has three children, what is the probability that the famil  [#permalink]

### Show Tags

31 Jan 2019, 17:47
Bunuel wrote:
If a family has three children, what is the probability that the family has at least one girl?

A. 1

B. 0.875

C. 0.75

D. 0.50

E. 0.375

We can use the formula:

P(at least one girl) = 1 - P(no girls)

P(no girls) = (1/2)^3 = 1/8.

P(at least one girl) = 1 - 1/8 = 7/8 = 0.875.

_________________

Scott Woodbury-Stewart
Founder and CEO

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Re: If a family has three children, what is the probability that the famil   [#permalink] 31 Jan 2019, 17:47
Display posts from previous: Sort by