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(b) Given that the student selected is a economics major, what is the probabilit

ID: 2896425 • Letter: #

Question

(b) Given that the student selected is a economics major, what is the probability that he is also an senior?

(If necessary, consult a list of formulas.)

(a)

(b)

Suppose that a certain college class contains students. Of these, are seniors, are economics majors, and are neither. A student is selected at random from the class. (a) What is the probability that the student is both a senior and an economics major?

(b) Given that the student selected is a economics major, what is the probability that he is also an senior?

Write your responses as fractions.

(If necessary, consult a list of formulas.)

(a)

(b)

Explanation / Answer

total students = 43

senior students = 28

economics students = 26

neither = 6

probability of senior = 28/43

probability of economics major = 26/43

probability of ( senior or economics major) = (43-6)/ 43 = 37/43

total probability would be

28/43+26/43 -37/43 = 17/43

b) given that student selected is economics major

probability that he is a senior is

prob ( senior | econ major ) = prob ( senior and econ) / prob (econ) = 17/43 / 26/43 = 17/26