Question

A marble is drawn at random from a box containing 10 red,30 white,20 blue& 15 orange marbles .find the probability that it is 1)orange or red 2)not red or blue

Answer 1

There are $10+30+20+15=75$ marbles.

1)

$$P(orange\ or\ red)=\dfrac{15+10}{75}=\dfrac{1}{3}$$

2)

$$P(not(\ red\ or\ blue))=P(orange\ or\ white)$$

$$=\dfrac{15+30}{75}=\dfrac{3}{5}$$