Question

A bag contains only black marbles and white marbles . Ezra reached into the bag without looking , got 30 marbles , and found that 12 of the marbles were black . Ezra is going to reach in the bag again and get one more marble .

what is the experimental probability that the marble will be black ?

a) 1/12
b) 2/5
c) 1/2
d) 2/3

Answer 1

B) 2/5
Coz 12/30 = 2/5

Answer 2

2/5

Since 12 out of 30 marbles were black, you can assume that the percentage of black marbles in the bag is 40% (Ex: 12/30=.4) The probability that the marble you pick is black is equal to the percentage of black marbles in the bag. 40% is equal to 2/5.