Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 26 Mar 2015, 18:00

### 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 June
Open Detailed Calendar

# [# 22] 2 Min. Challenge : Birthday

Author Message
TAGS:
CEO
Joined: 15 Aug 2003
Posts: 3470
Followers: 61

Kudos [?]: 697 [0], given: 781

[# 22] 2 Min. Challenge : Birthday [#permalink]  15 Mar 2004, 13:47
Rules

1. Time yourself
2. Solve seperately

Two girls have their birthdays in the same Week. It is known that one
of the girls was born on a Saturday. Determine the probability that both
were born on a Saturday.

1/2
1/4
1/7
1/13
1/14
Senior Manager
Joined: 23 Sep 2003
Posts: 294
Location: US
Followers: 1

Kudos [?]: 0 [0], given: 0

C - 1/7 - probability that second girl is born on a saturday.
Founder
Affiliations: AS - Gold, UA - Silver, HH-Diamond
Joined: 04 Dec 2002
Posts: 12714
Location: United States (WA)
GMAT 1: 750 Q49 V42
GPA: 3.5
WE: Information Technology (Hospitality and Tourism)
Followers: 2553

Kudos [?]: 11907 [0], given: 3825

Expert's post
Geethu wrote:
C) 1/7

<1 min

_________________

Founder of GMAT Club

Just starting out with GMAT? Start here... | Want to know your GMAT Score? Try GMAT Score Estimator
Need GMAT Book Recommendations? Best GMAT Books

Co-author of the GMAT Club tests

Have a blog? Feature it on GMAT Club!

GMAT Club Premium Membership - big benefits and savings

SVP
Joined: 30 Oct 2003
Posts: 1797
Location: NewJersey USA
Followers: 5

Kudos [?]: 41 [0], given: 0

I will go with 1/7

Few seconds.
GMAT Club Legend
Joined: 15 Dec 2003
Posts: 4315
Followers: 25

Kudos [?]: 209 [0], given: 0

Re: [# 22] 2 Min. Challenge : Birthday [#permalink]  15 Mar 2004, 17:03
praetorian123 wrote:
Rules

1. Time yourself
2. Solve seperately

Two girls have their birthdays in the same Week. It is known that one
of the girls was born on a Saturday. Determine the probability that both
were born on a Saturday.

1/2
1/4
1/7
1/13
1/14

The wording of the question was really to mislead us . Question is same as: Determine the probability that the second girl was born on a saturday given that first girl is born on a saturday. If 1/49 was among answer choices, then it could have maybe misled a few...
_________________

Best Regards,

Paul

CEO
Joined: 15 Aug 2003
Posts: 3470
Followers: 61

Kudos [?]: 697 [0], given: 781

Re: [# 22] 2 Min. Challenge : Birthday [#permalink]  15 Mar 2004, 17:11
sorry guys, but you got to think harder
SVP
Joined: 30 Oct 2003
Posts: 1797
Location: NewJersey USA
Followers: 5

Kudos [?]: 41 [0], given: 0

CEO
Joined: 15 Aug 2003
Posts: 3470
Followers: 61

Kudos [?]: 697 [0], given: 781

Re: [# 22] 2 Min. Challenge : Birthday [#permalink]  15 Mar 2004, 21:42
praetorian123 wrote:
Rules

1. Time yourself
2. Solve seperately

Two girls have their birthdays in the same Week. It is known that one
of the girls was born on a Saturday. Determine the probability that both
were born on a Saturday.

1/2
1/4
1/7
1/13
1/14

Well, i think this got to everyone. The answer is 1/13.

We know that at least one person has a birthday on Saturday. So for the probability that both were born on a Saturday, i first list the possibilities of birthdays for both girls .

G1-Girl 1
G2-Girl 2

G1 - G2
Sun-Sat
Mon-Sat
Tue-Sat
Wed-Sat
Thu-Sat
Fri-Sat
Sat-Sat
Sat-Sun
Sat-Mon
Sat-Tue
Sat-Wed
Sat-Thu
Sat-Fri

Note, we do not know which girl's birthday is on Saturday. So, we have to fix Each girls birthday on Saturday at a time and then list out the rest of the possibilities.

We have 13 possible combinations. Of those thirteen possible combinations that fulfill the condition, only one has two Saturdays, hence 1/13.
Founder
Affiliations: AS - Gold, UA - Silver, HH-Diamond
Joined: 04 Dec 2002
Posts: 12714
Location: United States (WA)
GMAT 1: 750 Q49 V42
GPA: 3.5
WE: Information Technology (Hospitality and Tourism)
Followers: 2553

Kudos [?]: 11907 [0], given: 3825

Re: [# 22] 2 Min. Challenge : Birthday [#permalink]  16 Mar 2004, 00:33
Expert's post
praetorian123 wrote:
praetorian123 wrote:
Rules

1. Time yourself
2. Solve seperately

Two girls have their birthdays in the same Week. It is known that one
of the girls was born on a Saturday. Determine the probability that both
were born on a Saturday.

1/2
1/4
1/7
1/13
1/14

Well, i think this got to everyone. The answer is 1/13.

We know that at least one person has a birthday on Saturday. So for the probability that both were born on a Saturday, i first list the possibilities of birthdays for both girls .

G1-Girl 1
G2-Girl 2

G1 - G2
Sun-Sat
Mon-Sat
Tue-Sat
Wed-Sat
Thu-Sat
Fri-Sat
Sat-Sat
Sat-Sun
Sat-Mon
Sat-Tue
Sat-Wed
Sat-Thu
Sat-Fri

Note, we do not know which girl's birthday is on Saturday. So, we have to fix Each girls birthday on Saturday at a time and then list out the rest of the possibilities.

We have 13 possible combinations. Of those thirteen possible combinations that fulfill the condition, only one has two Saturdays, hence 1/13.

_________________

Founder of GMAT Club

Just starting out with GMAT? Start here... | Want to know your GMAT Score? Try GMAT Score Estimator
Need GMAT Book Recommendations? Best GMAT Books

Co-author of the GMAT Club tests

Have a blog? Feature it on GMAT Club!

GMAT Club Premium Membership - big benefits and savings

Manager
Joined: 28 Jan 2004
Posts: 203
Location: India
Followers: 2

Kudos [?]: 12 [0], given: 4

Thats a really cool one.......
GMAT Club Legend
Joined: 15 Dec 2003
Posts: 4315
Followers: 25

Kudos [?]: 209 [0], given: 0

simple yet beautiful. Kudos
_________________

Best Regards,

Paul

Similar topics Replies Last post
Similar
Topics:
How to solve this question in 2min 1 17 Sep 2009, 14:24
HBS 2+2 5 18 Jun 2009, 21:43
HBS 2+2 Program 1 14 Sep 2007, 22:46
Time yourself.. under 2 mins 9 27 Aug 2006, 17:16
challenge 25 QUESTION 22 5 31 May 2006, 13:37
Display posts from previous: Sort by