Math Is Fun Forum

MKNB

Guest

Probability

Question 1 A box contains 4 red , 5 white and 6 green balls . The three balls are drawn from the box together . Find the probability that they may be
1) All of different colors
2) All of the same colour

Jaspers

Member

Registered: 2019-05-24

Posts: 54

Re: Probability

Hi MKNB.

1.
The total number of combinations of balls drawn is

To draw three different colours, you need to draw a red ball (which can be done in 4 ways), a white ball (which can be done in 5 ways), and a green ball (which can be done in 6 ways); so the number of ways to draw three different-coloured balls is 4 × 5 × 6 = 120.

Hence the probability is 120 divided by N.

2.
There are

ways of choosing 3 balls from x of the same colour, i.e. c(4) = 4 ways of choosing 3 red balls, c(5) = 10 ways of choosing 3 white balls, and c(6) = 20 ways of choosing 3 green balls.

Add them up and divide by N to get the probability of drawing three balls of the same colour.

Last edited by Jaspers (2019-06-07 20:49:28)

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