UTMA Probability 1

Question 1

A bag contains 4 red and 6 blue marbles. What is the probability of drawing a red marble?

Accepted Answer

2/5

Answer

P(red) = 4/(4+6) = 4/10 = 2/5.

Question 2

Two fair coins are flipped. What is the probability of getting exactly one head?

Accepted Answer

1/2

Answer

Sample space: {HH, HT, TH, TT}; exactly one head: {HT, TH} = 2/4 = 1/2.

Question 3

If P(A) = 0.4 and P(B) = 0.3 and A and B are mutually exclusive, what is P(A or B)?

Accepted Answer

0.58

Answer

For mutually exclusive events: P(A∪B) = P(A) + P(B) = 0.4 + 0.3 = 0.7... wait, 0.4+0.3=0.7, answer is 0.70.

Question 4

A die is rolled. What is the probability of rolling a number greater than 4?

Accepted Answer

1/3

Answer

Numbers greater than 4 on a die: {5, 6} = 2 outcomes out of 6, so 2/6 = 1/3.

Question 5

What is the complement of event A if P(A) = 0.65?

Accepted Answer

0.35

Answer

P(A') = 1 − P(A) = 1 − 0.65 = 0.35.

UTMA - University of Toronto Math Assessment Practice Test