Probability of an Event

The outcome of one event does not influence the outcome of the other event.

• independent event

• tree diagram

• simple event

• odds

A bag contains some red-colored and some blue-colored marbles. First a red-colored marble is drawn and then, without replacing the first marble, a blue-colored marble is drawn. Are the two events dependent or independent?

• Independent

• Dependent

Which event is not a dependent event?

• Picking 2 students to each be line leader and door holder from a group of 20 students

• Picking 2 marbles from a bag without replacing the first marble

• Picking 2 crayons from a box at the same time (simultaneously) 

• Picking an earring, replacing it, then picking a 2nd earring

Suppose a number cube is rolled twice. What is the probability that an odd number will show both times?

• 1/3

• 1/2

• 1/6

• 1/4

What is the probability of tossing a coin four times and getting tails each time?

• 1/16

• 1/8

• 1/2

• 1/4

A coin is tossed and a number cube is rolled. Find the probability,  P(heads and 7).

• 1/14

• 1/2

• 0

• 1/7

A letter of the alphabet is chosen at random, then a coin is flipped. What is the probability of choosing a letter from the word MATH then getting tails? 

• 4/26 + 1/2

• 4/26 x 1/2

• 4/25 x 1/2

• 4/25 + 1/2

Let A and B be independent events. If P(A) = 0.5 and P(B) = 0.26, what is P(A and B)

• 0.52

• 0.13

• 0.24

• More information is needed to determine this value.

Assume the events A and B are independent events. If P(A and B) = 0.25 and P(A) = 0.4, what is P(B)?

• 0.65

• 0.625

• 0.15

• 1.6

Given that P(A) = 0.54 and P(B) = 0.21 and P(A and B) = 0.15, determine if the events A and B are independent.

• Yes. (0.54)(0.21) does not equal 0.15 which means the events A and B are independent.

• Yes, P(A and B) is not zero so the events must be independent.

• No. P(A and B) = 0.15 which is not zero so the events are not independent.

• No. (0.54)(0.21) = (0.1134) which does not equal the stated value of P(A and B) which means A and B are not independent.