BUS 204 Week 8 Assignment

BUS 204 Week 8 Assignment | MiraCosta College 

1.

In practice problem #23, what is the STANDARD ERROR (also known as the Standard Deviation of Sample Means)? Round your answer to two decimal places.  81.32

2.

An Internet service provider states that the average number of hours its customers are online each day is

2.64.

Suppose a random sample of 14 of the company's customers is selected and the average number of hours that they are online each day is measured. The sample results are shown in the accompanying table.

3.11        3.63        2.29        7.67        4.63        1.97        7.88       

6.53        6.69        1.59        4.27        5.82        2.69        1.25       

Based on the sample of 14 customers, how much sampling error exists? Would you expect the sampling error to increase or decrease if the sample size was increased to 40?

Based on the sample of 14 customers, how much sampling error exists?

The sampling error for the given sample is

Would you expect the sampling error to increase or decrease if the sample size were 40?

A.

The sampling error would likely decrease because the sample size decreased.

B.

The sampling error would likely increase because the sample size decreased.

C.

The sampling error would likely decrease because the sample size increased.

Your answer is correct.

D.

The sampling error would likely increase because the sample size increased.

3.

A Real Estate Company has

20

listings for homes in a certain city. The number of days each house has been on the market without selling is shown in the accompanying table. Complete parts a through c below.

7              22           65           86           101         11           22           28           44           108        

59           6              72           70           18           67           71           73           100         45          

a. Considering these

20

values to be the population of interest, what is the mean of the population?

The population mean is

b. The company is making a sales brochure and wishes to feature

5

homes selected at random from the list. The number of days the 5 sampled homes have been on the market are listed below. If these

5

houses were used to estimate the mean for all

20,

what would the sampling error be?

70           44           100         6              101        

The sampling error for this sample is

 10.4510.45

days. (Round to two decimal places as needed.)

c. What is the range of possible sampling error if 5 homes are selected at random from the population?

The possible sampling error ranges from

days to

days.

4.

A normally distributed population has a mean of

400

and a standard deviation of

60.

a. Determine the probability that a random sample of size

16

selected from this population will have a sample mean less than

364.

b. Determine the probability that a random sample of size

25

selected from the population will have a sample mean greater than or equal to

426.

a.

b.

5.

Suppose the life of a particular brand of calculator battery is approximately normally distributed with a mean of

80

hours and a standard deviation of

11

hours. Complete parts a through c.

a. What is the probability that a single battery randomly selected from the population will have a life between

75

and

85

hours?

P(75≤x≤85)=

b. What is the probability that

4

randomly sampled batteries from the population will have a sample mean life of between

75

and

85

hours?

P(75≤x≤85)=

c. If the manufacturer of the battery is able to reduce the standard deviation of battery life from

11

to

9

hours, what would be the probability that

4

batteries randomly sampled from the population will have a sample mean life of between

75

and

85

hours?

6.

Given a population where the probability of success is

p=0.25,

calculate the probabilities below if a sample of

200

is taken.

a.            Calculate the probability the proportion of successes in the sample will be

less than

0.26.

b.            What is the probability the proportion of successes in the sample will be

greater than

0.27?

a. The probability the proportion of successes in the sample will be

less than

0.26

is

b. The probability the proportion of successes in the sample will be

greater than

0.27

is

7.

A survey is conducted from a population of people of whom

25%

have a college degree. The following sample data were recorded for a question asked of each person sampled, "Do you have a college degree?" Complete parts a and b.

No          Yes         No          No          No          No          Yes         Yes         No          No         

Yes         No          No          Yes         No          No          No          No          No          No         

No          No          No          No          No          No          No          No          No          Yes        

a. Calculate the sample proportion of respondents who have a college degree.

The sample proportion of respondents who have a college degree is

 0.20.2.

(Type an integer or a decimal.)

b. What is the probability of getting a sample proportion as extreme or more extreme than the one observed in part a if the population has

25%

with college degrees? If the sample proportion is greater than the population proportion, then the event of interest is the probability of obtaining the sample proportion or greater. If the sample proportion is less than the population proportion, then the event of interest is the probability of obtaining the sample proportion or less.

The probability is