At Least Probabilities

Find the mean (expected value) of the probability distribution.

• 85

• 83.2

• 87.1

• 84.4

The American Red Cross says that about 11% of the U.S. population has Type B blood. A blood drive is being held at your school. What is the probability that at least 2 of the first 10 blood donors has Type B blood? 

• 0.088

• 0.697

• 0.214

• 0.303 

If a fair coin is tossed 200 times, what is the probability that at least 99 but less than 110 heads turn up?

• 0.4945

• 0.4387

• 0.5153

• 0.4595

If you were to flip a coin 20 times, what is the probability you would get at least 13 heads?

• 94.23%

• 13.16%

• 5.77%

• 7.39%

Given the probability model in the table below, what is the expected value of the random variable?
  X        50          20        5
P(X)     0.1         0.3      0.6

• 14

• 4.67

• 5

• 7.5

What does the p stand for in the binomial probability formula?

• Number of trials

• Number of Successes

• Probability of Successes

• Probability of Failures

The following table presents a probability distribution for the number of pets each family has in a certain neighborhood. Find the probability that a randomly selected family has 1 or 2 pets.

• 0.2

• 0.4

• 0.1

• 0.5

A fair, 6-sided dice is thrown 120 times.

Roughly how many times would you expect the number 5 to come up?

• 6

• 10

• 12

• 20

A fair, 6-sided dice is thrown 18 times.

Roughly how many times would you expect the number 6 to come up?

• 1

• 3

• 6

Sam’s pencil case contains 3 red, 2 blue and 5 black pens. He takes a pen out without looking then puts it back 100 times. Roughly how many times would you expect him to pick up a red pen?

• 10

• 20

• 30

• 50