Bluebook SAT Test Probability and Conditional Probability 5

Question 1

A two-way table records 400 employees by department and satisfaction level.

Satisfied  Neutral  Dissatisfied
Engineering        80       40            30
Marketing          60       60            50
Operations         40       20            20

What is the probability a randomly selected employee is from Marketing and Dissatisfied?

Accepted Answer

1/8

Answer

Marketing & Dissatisfied = 50 out of 400 total; P = 50/400 = 1/8.

Question 2

P(A) = 0.6 and P(A and B) = 0.18. If A and B are independent, what is P(B)?

Accepted Answer

0.30

Answer

Since A and B are independent, P(B) = P(A and B)/P(A) = 0.18/0.6 = 0.30.

Question 3

A box has 3 red, 5 white, and 2 black balls. One ball is drawn and not replaced; then a second is drawn. What is the probability the second ball is red, given the first was white?

Accepted Answer

1/3

Answer

After removing a white ball, 9 balls remain: 3 red; P = 3/9 = 1/3.

Question 4

A game wheel has 4 red, 3 blue, and 1 green section. A player spins twice. What is the probability of getting green both times?

Accepted Answer

1/64

Answer

P(green) = 1/8; for two independent spins, P = (1/8)² = 1/64.

Question 5

In a class of 25 students, the probability that a randomly chosen student plays guitar is 0.32. What is the expected number of guitar players?

Accepted Answer

8

Answer

Expected value = 25 × 0.32 = 8.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Probability and Conditional Probability 5