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A hat contains 15 marbles, and each marble is numbered with one and on

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Joined: 02 Sep 2009
Posts: 59685
A hat contains 15 marbles, and each marble is numbered with one and on  [#permalink]

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Updated on: 10 Jul 2019, 23:13
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Difficulty:

25% (medium)

Question Stats:

77% (01:26) correct 23% (01:38) wrong based on 100 sessions

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A hat contains 15 marbles, and each marble is numbered with one and only one of the numbers 1, 2, 3. From a group of 15 people, each person selects exactly 1 marble from the hat.

Numbered Marble Number of People Who ----- Selected The Marble
1 ------------------------------- ------------------------------- 4
2 ------------------------------- ------------------------------- 5
3 ------------------------------- ------------------------------- 6

What is the probability that a person selected at random picked a marble numbered 2 or greater?

(A) 5/15
(B) 9/15
(C) 10/15
(D) 11/15
(E) 1

Source: Nova GMAT
Difficulty Level: 600

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Originally posted by Bunuel on 21 May 2017, 13:05.
Last edited by SajjadAhmad on 10 Jul 2019, 23:13, edited 1 time in total.
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Re: A hat contains 15 marbles, and each marble is numbered with one and on  [#permalink]

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21 May 2017, 13:27
For every three balls numbered 1,2 & 3 ; balls with value 2 and greater than 2 i.e 3 form 2/3 part of total balls which is 3 in this case.
So for 15 balls
Numbered 1 - 5 balls
Numbered 2 - 5 balls
Numbered 3 - 5 balls
Therefore probability of randomly choosing ball with 2 or 3 will be 2/3
In other words 10 balls / 15 balls

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Re: A hat contains 15 marbles, and each marble is numbered with one and on  [#permalink]

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21 May 2017, 18:50
Bunuel wrote:
A hat contains 15 marbles, and each marble is numbered with one and only one of the numbers 1, 2, 3. From a group of 15 people, each person selects exactly 1 marble from the hat.

Numbered Marble Number of People Who ----- Selected The Marble
1 ------------------------------- ------------------------------- 4
2 ------------------------------- ------------------------------- 5
3 ------------------------------- ------------------------------- 6

What is the probability that a person selected at random picked a marble numbered 2 or greater?

(A) 5/15
(B) 9/15
(C) 10/15
(D) 11/15
(E) 1

Lets consider the scenario when all the 15 person have picked 1 marble each (with either of number 1,2,3 on it)...selection of favorable case (greater than 1) would be 10/15
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Re: A hat contains 15 marbles, and each marble is numbered with one and on  [#permalink]

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21 May 2017, 20:41
1
Bunuel wrote:
A hat contains 15 marbles, and each marble is numbered with one and only one of the numbers 1, 2, 3. From a group of 15 people, each person selects exactly 1 marble from the hat.

Numbered Marble Number of People Who ----- Selected The Marble
1 ------------------------------- ------------------------------- 4
2 ------------------------------- ------------------------------- 5
3 ------------------------------- ------------------------------- 6

What is the probability that a person selected at random picked a marble numbered 2 or greater?

(A) 5/15
(B) 9/15
(C) 10/15
(D) 11/15
(E) 1

Hi,

mynamegoeson and irishiraj87
You are reading the question incorrectly..
We are looking for probability of picking a person who has picked number 2 or greater....

It's given 2 is picked by 5 people and 3 by 6 people..
So probability is $$\frac{5+6}{4+5+6}=\frac{11}{15}$$..

D
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Re: A hat contains 15 marbles, and each marble is numbered with one and on  [#permalink]

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21 May 2017, 22:34
1
There are a total of (5+6) = 11 people who have a marble number 2 or 3.
Rest 4 people have a marble numbered 1. Total people are 15.

So required probability = 11/15

Hence D
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Re: A hat contains 15 marbles, and each marble is numbered with one and on  [#permalink]

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23 May 2017, 17:20
1
Bunuel wrote:
A hat contains 15 marbles, and each marble is numbered with one and only one of the numbers 1, 2, 3. From a group of 15 people, each person selects exactly 1 marble from the hat.

Numbered Marble Number of People Who ----- Selected The Marble
1 ------------------------------- ------------------------------- 4
2 ------------------------------- ------------------------------- 5
3 ------------------------------- ------------------------------- 6

What is the probability that a person selected at random picked a marble numbered 2 or greater?

(A) 5/15
(B) 9/15
(C) 10/15
(D) 11/15
(E) 1

Since 5 people selected a marble numbered 2, the probability of selecting a marble numbered 2 is 5/15. Since 6 people selected a marble numbered 3, the probability of selecting a marble numbered 3 is 6/15.

Thus, the probability of selecting a marble numbered 2 or greater is 5/15 + 6/15 = 11/15.

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Re: A hat contains 15 marbles, and each marble is numbered with one and on  [#permalink]

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24 May 2017, 06:02
There are total 11 (5+6) marbles which are numbered 2 or higher.
Probability to select person at random = 1
Total number of marbles to choose from = 15
So the probability that a person selected at random picked a marble numbered 2 or greater = 1 * 11/15 = 11/15

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Re: A hat contains 15 marbles, and each marble is numbered with one and on  [#permalink]

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07 Apr 2019, 11:21
People <2 ; 4/15
so <2 ; 1-4/15 ; 11/15
IMO D

Bunuel wrote:
A hat contains 15 marbles, and each marble is numbered with one and only one of the numbers 1, 2, 3. From a group of 15 people, each person selects exactly 1 marble from the hat.

Numbered Marble Number of People Who ----- Selected The Marble
1 ------------------------------- ------------------------------- 4
2 ------------------------------- ------------------------------- 5
3 ------------------------------- ------------------------------- 6

What is the probability that a person selected at random picked a marble numbered 2 or greater?

(A) 5/15
(B) 9/15
(C) 10/15
(D) 11/15
(E) 1
Re: A hat contains 15 marbles, and each marble is numbered with one and on   [#permalink] 07 Apr 2019, 11:21
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