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 1 of 4.

Kigele yazidi said:   12 months ago
Total number of balls = 8 + 7 + 6,
=21.

Probability not red or green= number of events/sample space.
So, 7÷21 = 1/3.
(3)

Romeo said:   1 year ago
Thanks all for explaining.
(1)

Chris said:   2 years ago
@All.

Here, You can solve it in two ways.

Method 1:
Total number of balls = 7+8+6= 21.
Neither red nor green, that means it is blue,
Number of blue = 7,
Probability of blue = number of blue balls÷ total number of balls.

Probability of blue balls= 7/ 21.

1/3.

Method 2:
Total number of balls = 21.
Number of Red = 8.
Prob of selecting red = 8/21 or.
Number of Green = 6.
Prob of selecting green = 6/21 or 2/7.
Neither Red nor Green = 1-(prob of red+ prob of green).
1 - (8/21 + 6/21).
1 - 14/21 = 7/21 or 1/3.
(8)

Shiv said:   3 years ago
Neither red''️ nor green'' means (avoiding red and green) so we left out with blue means the one ball we have to pick up should be blue colour ball so.

P(E) = 7/21 = 1/3.

Rohit said:   5 years ago
How n(E) =7?

Ravindra said:   5 years ago
How can p(e) =7?

Because neither red nor green clearly means its blue.

Anitha said:   5 years ago
Total no.of balls =8+7+6=21,
Neither red nor green,
I.e.,we need to take 8,
Therefore p(e)=8/21.

Tharunteja said:   6 years ago
Guys it may be a wrong answer.

The actual correct answer;

Total no.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 (given neither red nor green) make a note this point.
therefore p(E) = 8/21.

Boopathy said:   7 years ago
Probability of selection Red or Green= 8+6=14 / 21 = 2/3.

Then how 1/3?
(1)

Anitha said:   7 years ago
How it is possible?


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