Bluebook SAT Test Probability and Conditional Probability 13

Question 1

A bag has 4 white and 6 black marbles. One marble is drawn and NOT replaced; then a second marble is drawn. What is the probability the second marble is white, given the first was also white?

Accepted Answer

1/3

Answer

After removing one white, 3 white remain out of 9 total; P = 3/9 = 1/3.

Question 2

The two-way table shows 600 college students by major and internship status.

Has Internship   No Internship
STEM                180              120
Non-STEM             80              220

What is the probability that a randomly chosen student is Non-STEM with no internship?

Accepted Answer

11/30

Answer

220/600 = 11/30.

Question 3

A basketball player makes free throws with probability 0.8. She shoots twice. What is the probability she makes exactly one?

Accepted Answer

0.32

Answer

P(make-then-miss) + P(miss-then-make) = 0.8(0.2) + 0.2(0.8) = 0.16 + 0.16 = 0.32.

Question 4

P(A) = 0.6, P(B) = 0.4. If A and B are mutually exclusive, what is P(A or B)?

Accepted Answer

1.00

Answer

Mutually exclusive: P(A or B) = P(A) + P(B) = 0.6 + 0.4 = 1.00.

Question 5

A group of 5 friends randomly lines up. What is the probability that a specific person, Zara, is first in line?

Accepted Answer

1/5

Answer

Each of the 5 positions is equally likely, so P(Zara first) = 1/5.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Probability and Conditional Probability 13