Bluebook SAT Test Probability and Conditional Probability 8

Question 1

A two-way table records 500 households by internet speed and streaming usage.

Streams Daily  Does Not Stream
High-speed internet         180              70
Low-speed internet           60             190

What is the probability a household streams daily?

Accepted Answer

12/25

Answer

Total streaming = 180 + 60 = 240 out of 500; P = 240/500 = 12/25.

Question 2

P(A) = 0.7. If A and B are independent and P(A and B) = 0.28, what is P(B)?

Accepted Answer

0.40

Answer

P(B) = P(A and B)/P(A) = 0.28/0.7 = 0.40.

Question 3

Three cards labeled 1, 2, and 3 are shuffled. Two cards are drawn one at a time without replacement. What is the probability the sum of the two cards equals 4?

Accepted Answer

1/3

Answer

Ordered pairs summing to 4: (1,3) and (3,1); total ordered pairs = 3×2 = 6; P = 2/6 = 1/3.

Question 4

A store's records show that 60% of customers buy clothing, 40% buy accessories, and 20% buy both. What is the probability a customer buys clothing but NOT accessories?

Accepted Answer

2/5

Answer

Clothing only = 0.60 − 0.20 = 0.40 = 2/5.

Question 5

The two-way table shows 360 athletes by sport and injury history.

Injured  No Injury
Contact         90        60
Non-contact     50       160

What is the probability a randomly selected athlete is in a contact sport, given they have no injury?

Accepted Answer

3/11

Answer

No injury total = 60 + 160 = 220; contact, no injury = 60; P = 60/220 = 3/11.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Probability and Conditional Probability 8