It is currently 17 Nov 2017, 20:07

### 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

# Each of the 30 students in a class is either male or female,

Author Message
TAGS:

### Hide Tags

Manager
Joined: 22 Jul 2009
Posts: 191

Kudos [?]: 284 [2], given: 18

Each of the 30 students in a class is either male or female, [#permalink]

### Show Tags

21 Sep 2009, 18:32
2
KUDOS
2
This post was
BOOKMARKED
00:00

Difficulty:

65% (hard)

Question Stats:

61% (01:19) correct 39% (01:49) wrong based on 147 sessions

### HideShow timer Statistics

Each of the 30 students in a class is either male or female, and has blonde, brown, or red hair. If one student is to be randomly selected from the class, what is the probability that the student will either be female or have brown hair?

(1) The probability that the student will both be female and have brown hair is 0.1.
(2) The probability that the student will be female minus the probability that the student will have brown hair is 0.25.

Source: Jeff Sackmann's GMAT Extreme Challenge
[Reveal] Spoiler: OA

_________________

Please kudos if my post helps.

Last edited by powerka on 22 Sep 2009, 12:20, edited 1 time in total.

Kudos [?]: 284 [2], given: 18

Manager
Joined: 10 Aug 2009
Posts: 129

Kudos [?]: 75 [2], given: 10

Re: Probability Problem - Extreme Challenge - Each of the 30 ... [#permalink]

### Show Tags

21 Sep 2009, 19:36
2
KUDOS
We have to find the following probability:

P(Female or Brown Hair)=P(Female)+P(Brown hair)-P(Female with brown hair)

Statement 1 - gives the value of P(Female with brown hair)=10% but we do not know P(Female) and P(Brown hair).
Statement 2 - states that P(Female)-P(Brown hair)=25%. not sufficient since we do not know P(female with brown hair) and we do not know either P(female) or P(brown hair)

Combined - still not sufficient. We need to know either P(Female) or P(Brown hair) in order to solve for P(Female or Brown hair)

Kudos [?]: 75 [2], given: 10

GMAT Tutor
Joined: 24 Jun 2008
Posts: 1339

Kudos [?]: 1994 [1], given: 6

Re: Probability Problem - Extreme Challenge - Each of the 30 ... [#permalink]

### Show Tags

21 Sep 2009, 21:28
1
KUDOS
Expert's post
This question is, mathematically speaking, essentially identical to a GMATPrep problem:

www.beatthegmat.com/gmat-prep-q-8-proba ... t4890.html
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

Kudos [?]: 1994 [1], given: 6

Director
Joined: 01 Apr 2008
Posts: 872

Kudos [?]: 860 [1], given: 18

Name: Ronak Amin
Schools: IIM Lucknow (IPMX) - Class of 2014
Re: Probability Problem - Extreme Challenge - Each of the 30 ... [#permalink]

### Show Tags

22 Sep 2009, 12:08
1
KUDOS
eh! I was wondering what does 0:10 and 0:25 mean? : means . here...guess the poster must change the symbols, its confusing.

Kudos [?]: 860 [1], given: 18

Manager
Joined: 22 Jul 2009
Posts: 191

Kudos [?]: 284 [1], given: 18

Re: Probability Problem - Extreme Challenge - Each of the 30 ... [#permalink]

### Show Tags

22 Sep 2009, 12:20
1
KUDOS
Economist wrote:
eh! I was wondering what does 0:10 and 0:25 mean? : means . here...guess the poster must change the symbols, its confusing.

Typo. Its 0.1 and 0.25. Will edit.
_________________

Please kudos if my post helps.

Kudos [?]: 284 [1], given: 18

Intern
Joined: 22 Apr 2013
Posts: 7

Kudos [?]: 1 [0], given: 3

Re: Each of the 30 students in a class is either male or female, [#permalink]

### Show Tags

29 Jun 2013, 03:31
i chose E.
from first statement we can deduce there are 3 female with brown hair (0.1=1/10=3/30)
but v can neither find out no. of females(blonde+red+brown) nor no. of students with brown hair (female + male). not sufficient

2nd statement
female/30 - brown/30=0.25=1/4=15/60
hence 2female-2brown = 15
2 variables in one equation. not sufficient

even together v cant find the solution.
so E
temme if i did anything wrong
cheers

Kudos [?]: 1 [0], given: 3

Math Expert
Joined: 02 Sep 2009
Posts: 42248

Kudos [?]: 132521 [0], given: 12324

Re: Each of the 30 students in a class is either male or female, [#permalink]

### Show Tags

29 Jun 2013, 03:51
powerka wrote:
Each of the 30 students in a class is either male or female, and has blonde, brown, or red hair. If one student is to be randomly selected from the class, what is the probability that the student will either be female or have brown hair?

(1) The probability that the student will both be female and have brown hair is 0.1.
(2) The probability that the student will be female minus the probability that the student will have brown hair is 0.25.

Source: Jeff Sackmann's GMAT Extreme Challenge

"Stolen" GMAT Prep question:
Quote:
Each of the 25 balls in a certain box is either red, blue or white and has a number from 1 to 10 painted on it. If one ball is to be selected at random from the box, what is the probability that the ball selected will either be white or have an even number painted on it?

(1) The probability that the ball will both be white and have an even number painted on it is 0

(2) The probability that the ball will be white minus the probability that the ball will have an even number painted on it is 0.2

Discussed here: each-of-the-25-balls-in-a-certain-box-is-either-red-blue-or-99044.html
_________________

Kudos [?]: 132521 [0], given: 12324

Re: Each of the 30 students in a class is either male or female,   [#permalink] 29 Jun 2013, 03:51
Display posts from previous: Sort by