1

Chapter 5:

1)

Flip a coin three times.

(a)

Find the sample space.

(b)

Let X be the number of tails. Find the probability distribution for X.

(c)

Draw a graph for the distribution.

(d)

Find the mean, variance and standard deviation for X.( No credits will be

given if you did

not show your work.)

(e)

Find the probability of getting at least one tail.

(f)

Find the probability of getting at most two tails.

2)

From past experience, a company has found that in cartons of transistors, 93%

contain no defective transistors,

4% contain one defe

ctive transistor, 2% contain

two defective transistors, and 1% contain three defective transistors.

(a)

Find the mean defective transistors.

(b)

About how many extra transistors per day would the company need to

replace the defective ones if it uses 25 cartons per

day?

3)

If Mary rolls doubles when she tosses two dice, she wins $5. For the game to be

fair, how much should Mary pay to play the game?

4)

In a Gallup Survey, 90% of the people interviewed were unaware that maintaining

a healthy weight could reduce the risk o

f stroke. If 15 people are selected at

random,

(a)

find the probability that at least 5 are unaware that maintaining a proper

weight could reduce the risk of stroke.

(b)

Find the probability that exactly 7 are unaware that maintaining a proper

weight could reduce

the risk of stroke.

5)

In a restaurant, a study found that 42% of all patrons smoked. If the seating

capacity of the restaurant is 150 people.

(a)

Find the mean, and standard deviation of the number of smokers.

(b)

About how many seats should be available for smoki

ng customers?

6)

In a survey, 58% of American adults said they had never heard of the Internet. If

20 American adults are selected at random,

(a)

find the probability that exactly 12 will say they have never heard of the

Internet.

(b)

Find the probability that at l

east three will say they have never heard of the

Internet.

Answer

Answer

Answer

Chapter 5

1

HHH,HHT,HTH,THH,HTT,THT,

TTH,TTT; 1.5, 0.75, 0.87; 7/8, 7/8

2

0.11, 3

3

$0.83

4

Almost 1; 0.00003

5

63, 6.04, 63 seats

6

0.177, almost 1

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