a biased die with faces numbered 1 to 6 is rolled once. the figures below give the probability

Question

the figures below give the probability of obtaining each of the numbers on the die after a single roll. what is the probability of obtaining a 3 or 4.

1        2           3             4             5           6

0.2     0.15       0.15        0.25         0.1        0.15

Answer 1

Since the two outcomes are mutually exclusive (if you get a 3, you can't also get a 4 and vice versa), you can add their probabilities together to get the probability of either outcome occurring:

 

P(3) = 0.15

P(4) = 0.25

 

P(3 or 4) = P(3) + P(4) = 0.15 + 0.25 = 0.4