(Q8) A box contains 5 red marbles, 8 white marbles and 4 green marbles. One marble is taken out of the box at random. What is the probability that the marble taken out will be (i) red? (ii) white? (iii) not green?

Answer :

Total number of marbles in the box = 5 red + 8 white + 4 green =

Number of total outcomes in drawing a marble at random from the box =.

(i) Number of red marbles =

Number of favourable outcomes in drawing a red ball =

∴ Probability of getting a red ball P(R) =
No. of favourable outcomes
Total no. of outcomes
 =

(ii) Number of white marbles =

Number of favourable outcomes in drawing a white marble =

∴ Probability of getting a white marble P(W) =

(iii) Number of 'non-green' marbles = 5 red + 8 white =

Number of outcomes favourable to drawing a non-green marble =.

∴ Probability of getting a non- green marble

P(non - green) =
No. of favourable outcomes
Total no. of outcomes
P(non - green) =

(or)

Probability of getting a green ball =
No. of green balls
Total no. of balls
=
Now P(G) =
and P(G) + P(Ḡ) = 1
∴ P(Ḡ) = 1 - P(G) = 1 -
=