﻿ There are two balls in an urn whose colours are not known (each ball can be either white or black). A white ball is put into the urn. A ball is drawn from the urn. The probability that it is white is : Kaysons Education

# There Are Two Balls In An Urn Whose Colours Are Not Known (each Ball Can Be Either White Or Black). A White Ball Is Put Into The Urn. A Ball Is Drawn From The Urn. The Probability That It Is White Is

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## Question

### Solution

Correct option is

2/3

Let Ei (0 ≤ i ≤ 2) denote the vent that urn contains i white and (2 – i) black balls. Let A denote the event that a white ball is drawn from the urn.

We have    P(Ei) = 1/3      for     i = 0, 1, 2 and

By the total probability rule,

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