Question

A jar containing 8 marbles of which 4 red and 4 blue marbles are there. Find the probability of getting a red given the first one was red too. A jar containing 8 marbles of which 4 red and 4 blue marbles are there. Find the probability of getting a red given the first one was red too.

Answer 1

Answer:

3/7

Step-by-step explanation:

Total marbles before picking = 8 (4 R and 4 B)

It is given that 1st marble that was picked is "RED".

Total marbles after picking 1st marble = 7 (3 R and 4 B)

Therefore, Probability = 3/7

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Answer 2

Given:

Total number of marbles = 8

Total number of red marbles = 4

Total number of blue marbles = 4

To find:

Probability of getting a red given the first one was red too

Solution:

Let, getting a red marble in the first turn be = P(A)

Let, getting a blue marble in the second turn be = P(B)

Therefore,

P(A) = 4/8

P(B) = 3/7

P (A and B)

= 4/8 × 3/7

= 3/14

P(B/A) = P (A and B)/P (A)

= 3/14/1/2

= 3/7

Answer: Probability of getting a red given the first one was red too is 3/7