Answer to Question #309285 in Statistics and Probability for Geki

Question

An individual is handover a bag filled with balls of different colours. The table below

gives the probability that a randomly chosen ball is of a specific colour, along with a

missing probability value of picking a ball of white colour.

Colour Red Yellow Green Orange Blue White

Probability 0.2 0.2 0.1 0.1 0.3 ?

Answer the following questions:

(i) What value must the missing probability be?

(ii) If a ball is drawn at random from the bag, what is the probability of each of the

following events?

I. It is either Blue or Red in colour.

II. It is notYellow in colour.

III. It is neither Orange nor White in colour.

IV. It is either Blue or Red or Yellow or Green or Orange or White.

Answer 1

(i)                The sum of probabilities is 1, from which the missing probability is

1-0.2-0.2-0.1-0.1-0.3=0.1

(ii)             I: 0.2+0.3=0.5

II: 1-0.2=0.8

III: 1-(0.1+0.1)=0.8

IV: These are all possible colors, probability is 1