Question

1.Among 90 pieces of mail delivered to the library of a college,50 are addressed to the faculty of Business Administration and 40 are addressed to the Communication faculty.if two of these pieces of mail are delivered to the Dean's office by mistake,and the selection is random,what are the probabilities that:
I.Both of them should have been delivered to the faculty of Business Administration.
II.both of them should have been delivered to the faculty of Arts.
III.One should have been delivered to the faculty of Arts and other to the Faculty of Business Administration.


2.In a statistics class,there are 18 juniors and 10 seniors;6 of the seniors are females and 12 of the juniors are males.if a student is selected at random,find the probability of selecting
I.a junior or a female.
II.a senior or a female.
III.a junior or a senior.

Answer 1

1. If the events are independent, the probability of both/all events occurring is determined by multiplying the probabilities of the individual events.

I. (50/90)^2 = ?
II. Generalize from I.
III. (50/90)(40/90) = ?

2. Either-or probabilities are found by adding the individual probabilities.


III. 18/28 + 10/28 = ?