Probability Math

Question

You roll a 6-sided die. What is P(greater than 4 or factor of 35)?

Answer 1

Hello Bla,

This can be solved using the addition rule: P(A or B) = P(A) + P(B) - P(A and B)

P(greater than 4 or factor of 35) = P(greater than 4) + P(factor of 35) - P(greater than 4 and factor of 35)

The factor of 35 that are between 1 and 6 are 1 and 5

P(greater than 4) = P(rolling a 5 or 6) = 1/6 + 1/6 = 2/6

P(factor of 35) = P(rolling a 1 or a 5) = 1/6 + 1/6 = 2/6

P(greater than 4 and factor of 35) = P(rolling a 5) = 1/6

2/6 + 2/6 - 1/6 = 3/6 =1/2

Thus, the probability of rolling a number (greater than 4 or factor of 35 is 1/2