It is currently 18 Nov 2017, 09:08

### 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

# of the students at a certain school, 50% of the students are

Author Message
VP
Joined: 30 Sep 2004
Posts: 1480

Kudos [?]: 425 [0], given: 0

Location: Germany
of the students at a certain school, 50% of the students are [#permalink]

### Show Tags

15 Mar 2005, 08:13
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

of the students at a certain school, 50% of the students are in class a, 30% of the students are in class b, 20% of the students are in class c. of the students in class a, 20% are wearing eyeglasses. of the students in class b, 10% are wearing eyeglasses. of the students c, 10% are wearing eyeglasses. if a student is selected at random, what is the probability that the student is wearing eyeglasses ?

Kudos [?]: 425 [0], given: 0

GMAT Club Legend
Joined: 07 Jul 2004
Posts: 5032

Kudos [?]: 452 [0], given: 0

Location: Singapore

### Show Tags

15 Mar 2005, 11:59
I got 9/50.

My solution is in a word document as I used a table to solve the question. I can't display the table properly here. However, I also can't find a button to let me make an attachement. I don't know if I got my rights to attach files disabled or I am pure blind and can't find it
Maybe the moderators can help me with the attachement.

Kudos [?]: 452 [0], given: 0

Intern
Joined: 17 Feb 2005
Posts: 28

Kudos [?]: 44 [0], given: 0

Location: SE Michigan

### Show Tags

15 Mar 2005, 12:09
A:B:C
50:30:20

In A
Glasses: No Glasses
10:40

In B
Glasses: No Glasses
3:27

In C
Glasses: No Glasses
2:18

So in total,

15 wear glasses out of 100

req. probability= 15/100

Kudos [?]: 44 [0], given: 0

GMAT Club Legend
Joined: 07 Jul 2004
Posts: 5032

Kudos [?]: 452 [0], given: 0

Location: Singapore

### Show Tags

15 Mar 2005, 12:14
ywilfred wrote:
I got 9/50.

My solution is in a word document as I used a table to solve the question. I can't display the table properly here. However, I also can't find a button to let me make an attachement. I don't know if I got my rights to attach files disabled or I am pure blind and can't find it
Maybe the moderators can help me with the attachement.

Made a mistake with my table. Yes, answer is 3/20 (15/100). But I'm still not able to attach my document. Can someone tell me why ?

In any case, my working is the same as amit_upasan's.

Kudos [?]: 452 [0], given: 0

Manager
Joined: 15 Feb 2005
Posts: 245

Kudos [?]: 8 [0], given: 0

Location: Rockville

### Show Tags

15 Mar 2005, 12:40
A:(prob of picking a student from class A)*(prob of picking a student with glasses)=2/10*1/2
do the same for a student from class B and C
B: 3/10*1/10
C: 2/10*1/10
A+B+C

Kudos [?]: 8 [0], given: 0

VP
Joined: 30 Sep 2004
Posts: 1480

Kudos [?]: 425 [0], given: 0

Location: Germany

### Show Tags

16 Mar 2005, 08:38
0,5*0,2+0,3*0,1+0,2*0,1=0,15=15%

now it is easy to see the connection to the other question => http://www.gmatclub.com/phpbb/viewtopic.php?t=14826

Kudos [?]: 425 [0], given: 0

Manager
Joined: 17 Dec 2004
Posts: 71

Kudos [?]: 14 [0], given: 0

### Show Tags

16 Mar 2005, 21:49
I got 3/20 as well:

A - 50% students, 20% wear glasses = 10% of total students
B - 30% students, 10% wear glasses = 3% of total students
C - 20% students, 10% wear glasses = 2% of total students

which leads to 15% of total students wear glasses

15/100 = 3/20

Kudos [?]: 14 [0], given: 0

16 Mar 2005, 21:49
Display posts from previous: Sort by