STATISTICS

Question 1

PROBABILITIES . . . To determine the probability of two things happening in a row, multiply the probabilities

E.g., if there are 5 red marbles in a bowl with 16 marbles, the probability of selecting two red marbles in a row is…

Answer 1

5/16 x 4/15

20/240 = 10/120 = 1/12

Question 2

To determine the probability of TWO possibilities happening, ADD the probabilities

E.g., if a bowl has 16 marbles, with 5 red marbles and 4 white marbles, what is the probability that either 2 red marbles in a row or 2 white marbles in a row will come out?

Answer 2

Red marbles: 5/16 x 4/15 = 1/12

White marbles: 4/16 x 3/15 = 12/240 = 6/120 = 3/60 = 1/20

Add the probabilities:

1/12 + 1/20 = 5/60 + 3/60 = 8/60 = 4/30 = 2/15