Question

A bag contains $9$ discs of which $4$ are red, $3$ are blue and $2$ are yellow. A disc is drawn at random from the bag: Calculate the probability that it will be (i) yellow (ii) not blue and (iii) either red or blue.

Answer 1

probability of drawing a colour disc =$\frac{numberofthatcolourdics}{totalnumberofdics}$

therefore

the probability of drawing yellow=$\frac{2}{9}$,

probability of drawing red=$\frac{4}{9}$,

probabiity of drawing blue=$\frac{3}{9}$

probability of not drawing blue =$1-\frac{3}{9}=2/3$

probability of drawing either red or blue=$\left[\frac{4}{9}\right]+\left[\frac{3}{9}\right]=\frac{7}{9}$