Aptitude - Probability - Discussion

Discussion Forum : Probability - General Questions (Q.No. 3)
3.
In a box, there are 8 red, 7 blue and 6 green balls. One ball is picked up randomly. What is the probability that it is neither red nor green?
1
3
3
4
7
19
8
21
9
21
Answer: Option
Explanation:

Total number of balls = (8 + 7 + 6) = 21.

Let E = event that the ball drawn is neither red nor green
= event that the ball drawn is blue.

n(E) = 7.

P(E) = n(E) = 7 = 1 .
n(S) 21 3

Discussion:
36 comments Page 4 of 4.

Angamuthu SURESH said:   1 decade ago
Total number of balls = (8 + 7 + 6)
= 21.
Let E = event that the ball drawn is neither red nor green
=event that the ball drawn is red.
Therefore, n(E) = 8.
P(E) = 8/21.

Farah said:   1 decade ago
Please all students read question carefully what he ask in question. He said that 8 red, 6 green, 7 blue total=21 probability ?

He said neither from red and green so only one option is 7 blue.

7c1 which is n(a)=7 and n(S)=21c1=21

Formula is prob. p(A)=n(A)/n(S)

7/21 = 1/3.

Muhammad Imran Tariq said:   1 decade ago
Sample= 8+7+6=21.

Probability of selection Red and Green= 8+6=14 / 21 = 2/3.

Not selection of Red and Green. Simple subtracts 1 from 2/3.

1 - 2/3= 1/3 (Answer).

Mangesh Modiraj said:   1 decade ago
@Nandini & @Monica.

In example clearly mentioned that the ball ins neither red nor green.

i.e blue.

We have 7 blue balls.

Therefore n(E) = 7.

Bibekpangeni said:   1 decade ago
What is the meaning of probability?

Durga said:   1 decade ago
Total balls are - 21

So the probability of getting one ball is -21c1 = 21.

That one ball is neither red nor green means blue ball.

Posing one blue ball from 7 blue balls is 7c1 = 7.

Our required ans=7/21=1/3.


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