Question

a bag consists of 4 red, 5 white, and 3 blue marbles. find the probability of obtaining a white or a blue marble in a single draw.

Answer 1

total=4+5+3=12 marbles

P(white or blue) = (total white or blue marbles) / total
P(w or b) = (5+3) / 12
P(w or b) = 8/12
P(w or b) = 2/3

2/3, or 67%.

Answer 2

P(white)=5/12
P(blue)=3/12

P(total)=(5+3)/12=8/12=2/3