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

 It is currently 03 Jul 2015, 19:55

### 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

# Probability

Author Message
TAGS:
Manager
Joined: 21 Mar 2006
Posts: 131
Followers: 1

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

Probability [#permalink]  01 Apr 2006, 21:48
Here's a nother example question.

If the probability of rain on any given day in City X is 50%, what is the probability that it rains on exactly 3 days in a 5-day period.

a. 8/125
b. 2/25
c. 5/16
d. 8/25
e. 3/4

I got the right answer by guessing but now i think i probably should learn it the right way
_________________

A.P.

GMAT Club Legend
Joined: 07 Jul 2004
Posts: 5068
Location: Singapore
Followers: 23

Kudos [?]: 194 [0], given: 0

There's a Binomial Distribution example in the Permutation, Combination and Probabilities sticky. Try reading it and see if you can solve this problem.

Example:
The probability of raining is 0.3 and not raining is 0.7. What is the probability of getting three days of rains among seven days?
C(7, 3)*0.3^3*0.7^4
Director
Joined: 05 Feb 2006
Posts: 899
Followers: 1

Kudos [?]: 54 [0], given: 0

Total number of possibilities = 32..... 2*2*2*2*2 (five days, each day has an equal chance to be a rain day or dry day)

Favourable outcomes = 10 (number of ways to pick 3 rain days out of 5 in any order... 5C3)

Total probability = 10/32.... 5/16
VP
Joined: 29 Apr 2003
Posts: 1403
Followers: 2

Kudos [?]: 18 [0], given: 0

Yep.. Its C.

I like ur photo SimaQ
Director
Joined: 05 Feb 2006
Posts: 899
Followers: 1

Kudos [?]: 54 [0], given: 0

sm176811 wrote:
Yep.. Its C.

I like ur photo SimaQ

I like it also
Manager
Joined: 21 Mar 2006
Posts: 131
Followers: 1

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

yeap its C... i didnt know it was a combination problem... thats probably why i wasnt getting it.. thanks
_________________

A.P.

Similar topics Replies Last post
Similar
Topics:
probability 4 01 Oct 2006, 16:59
Probability 6 29 Aug 2006, 14:42
Probability 6 10 Jan 2006, 15:24
probability 4 08 Dec 2005, 05:14
Probability 8 19 Aug 2005, 11:12
Display posts from previous: Sort by