A bucket contains 10 brown balls, 8 green balls, and 12 red balls and one ball is picked randomly without looking. The probability that the picked ball will be brown is _______.
13
Total number of balls = 10 + 8 + 12 = 30 = n(S)
Total number of brown balls = 10 = n(B)
Let the probability of the picked brown ball be P(B).
Therefore,
P(B) = n(B)n(S)=1030=13=0.33.