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Mathematics · Probability · NCERT Examples

Example 2

A complete, independently verified solution for NCERT Example 2.

Mathematics · Chapter 14 · NCERT Examples

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NCERT Example

Example 2

coloured balls · elementary events

A bag contains one red ball, one blue ball and one yellow ball, all of the same size. Kritika draws one ball without looking. Find the probability of drawing (i) the yellow ball, (ii) the red ball and (iii) the blue ball.

Solution

Board-exam working:

The three balls are equally likely to be selected.

S={Y,R,B},n(S)=3S=\{Y,R,B\},\qquad n(S)=3

Each required event has exactly one favourable outcome.

P(Y)=13P(Y)=\frac13
P(R)=13P(R)=\frac13
P(B)=13P(B)=\frac13

Final answer

P(Y)=P(R)=P(B)=13\boxed{P(Y)=P(R)=P(B)=\frac13}