Question

Your English teacher has decided to randomly assign poems for the class to read. The syllabus includes four poems by Shakespeare, five poems by Coleridge, two poems by Tennyson, and two poems by Lord Byron. What is the probability that you will be assigned a poem by Shakespeare, and then a poem by Tennyson?

Answer 1

The probability of event A and B to both occur is denoted as P(A ∩ B) = P(A) P(B|A). It is the probability that Event A occurs times the probability that Event B occurs, given that Event A has occurred.

So, to find the probability that you will be assigned a poem by Shakespeare and by Tennyson, let Event A = the event that a Shakespeare poem will be assigned to you; and let Event B = the event that the second poem that will be assigned to you will be by Tennyson.

At first, there are a total of 13 poems that would be randomly assigned in your class. There are 4 poems by Shakespeare, thus P(A) is 4/13.
After the first selection, there would be 13 poems left. Therefore, P(B|A) = 2/12
Based on the rule of multiplication,
P(A ∩ B) = P(A) P(B|A)P(A ∩ B) = 4/13 * 2/12
P(A ∩ B) = 8/156
P(A ∩ B) = 2/39

The probability that you will be assigned a poem by Shakespeare, then a poem by Tennyson is 2/39 or 5.13%.