Bluebook SAT Test Probability and Conditional Probability 2

Question 1

A spinner has 8 equal sections numbered 1–8. What is the probability of landing on a prime number?

Accepted Answer

1/2

Answer

Primes from 1–8 are 2, 3, 5, 7 — that's 4 values, so P = 4/8 = 1/2.

Question 2

Of 500 adults surveyed, 300 exercise regularly and 200 do not. Among those who exercise, 240 reported good health; among those who don't, 60 reported good health. What is the probability that a randomly selected adult who reports good health exercises regularly?

Accepted Answer

4/5

Answer

Total reporting good health = 240 + 60 = 300; exercisers = 240, so P = 240/300 = 4/5.

Question 3

A box contains 5 defective and 15 non-defective items. Two items are selected at random without replacement. What is the probability that the first is defective and the second is non-defective?

Accepted Answer

15/76

Answer

P(1st defective) = 5/20; P(2nd non-defective | 1st defective) = 15/19; product = 75/380 = 15/76.

Question 4

In a group of 80 people, 50 drink coffee and 40 drink tea. If the probability of drinking both is 0.25, how many people drink coffee or tea?

Accepted Answer

70

Answer

P(both) = 0.25 means 20 people; P(coffee or tea) count = 50 + 40 − 20 = 70.

Question 5

The two-way table shows 400 students categorized by grade and club membership.

In Club  Not in Club
Grade 9-10       80          120
Grade 11-12     100          100

A student is chosen at random. What is the probability the student is in a club, given they are in Grade 11–12?

Accepted Answer

1/2

Answer

Grade 11–12 total = 100 + 100 = 200; in club = 100, so P = 100/200 = 1/2.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Probability and Conditional Probability 2