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

 It is currently 02 Jul 2015, 15:29

### 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

# Ps - Probablity

Author Message
TAGS:
Senior Manager
Joined: 14 Apr 2005
Posts: 418
Location: India, Chennai
Followers: 1

Kudos [?]: 6 [0], given: 0

Ps - Probablity [#permalink]  05 Jan 2006, 03:21
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Find the probability of getting a larger number than the previous number every time, when an unbiased die is thrown three times.

(a) 1/18 (b) 15/216

(c) 25/216 (d) 5/54

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

Kudos [?]: 193 [0], given: 0

Possibilites:

First throw is 1: 2,3 - 2,6; 3,4 - 3,6; 4,5 - 4,6; 5,6 --> Total: 10 ways

First throw is 2: 3,4 - 3,6; 4,5 - 4,6, 5,6 --> Total: 6 ways

First throw is 3: 4,5 - 4,6, 5,6 --> Total: 3 ways

First throw is 4: 5,6 -> Total: 1 ways

First throw is 5: No way

First throw is 6: No way

Total number of possibilites = 20

Total number of combinations with three rolls of a die = 6*6*6 = 216

Probability = 20/216 = 10/108 = 5/54 (D)

P.S: This method may not look elegant, but it's extremely fast.
Director
Joined: 04 Oct 2005
Posts: 586
Location: Chicago
Followers: 1

Kudos [?]: 5 [0], given: 0

5/54..

Here's my working

Prob of getting a number on the first throw= 1/6

Prob of getting a no higher on the second throw = 5C1/6 ( Only 5 nos r left)=5/6

Prob of getting a no higher than 3rd throw= 4C1/6 (Only 4 r left_=4/6

1/6*5/6*4/6=5/54
Similar topics Replies Last post
Similar
Topics:
ps-probability 4 13 Feb 2006, 11:07
Probability-ps 10 10 Feb 2006, 05:08
ps-Probability 9 09 Feb 2006, 16:43
probability ps 17 09 Jan 2006, 00:53
Probability Ps 1 16 Nov 2005, 23:12
Display posts from previous: Sort by