Bluebook SAT Test Probability and Conditional Probability 16

Question 1

A quality inspector finds that 3% of products are defective. If 4 products are tested independently, what is the probability that exactly 1 is defective?

Accepted Answer

0.1128

Answer

C(4,1)(0.03)^1(0.97)^3 = 4(0.03)(0.912673) ≈ 0.1128.

Question 2

The two-way table shows 400 employees by shift and error rate.

0 Errors   1+ Errors
Day Shift         150          50
Night Shift        80         120

Given an employee made at least one error, what is the probability they work the night shift?

Accepted Answer

12/17

Answer

1+ errors total = 50 + 120 = 170; P(night | error) = 120/170 = 12/17.

Question 3

Events H and K are independent. P(H) = 0.6 and P(K) = 0.7. What is P(neither H nor K)?

Accepted Answer

0.12

Answer

P(not H) × P(not K) = 0.4 × 0.3 = 0.12.

Question 4

A bag contains 5 red, 4 white, and 1 blue marble. A marble is drawn at random. What is the probability it is NOT white?

Accepted Answer

3/5

Answer

Non-white = 5 + 1 = 6 out of 10; P = 6/10 = 3/5.

Question 5

Two events A and B satisfy P(A) = 0.5, P(B | A) = 0.4, and P(B | not A) = 0.2. What is P(B)?

Accepted Answer

0.30

Answer

P(B) = P(B|A)P(A) + P(B|not A)P(not A) = 0.4(0.5) + 0.2(0.5) = 0.20 + 0.10 = 0.30.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Probability and Conditional Probability 16