Week 3

#7 (Q)

According to an NRF survey conducted by BIG research, the average family spends about $237on electronics (computers, cell phones, etc.) in back-to-college spending per student. Suppose back-to-college family spending on electronics is normally distributed with a standard deviation of $54. If a family of a returning college student is randomly selected, what is the probability that:

(a)They spend less than $165on back-to-college electronics?

(b)They spend more than $380on back-to-college electronics?

(c)They spend between $135and $175on back-to-college electronics?

(Round the values of z to 2 decimal places. Round your answers to 4 decimal places.)

(a)P(x<165) =_________

enter the probability that they spend less than $165on back-to-college electronics

(b)P(x>380) =_____________

enter the probability that they spend more than $380on back-to-college electronics

(c)P(135<x<175) =________________

enter the probability that they spend between $135and $175on back-to-college electronics

Question #2 (H)

Determine the Pearson product-moment correlation coefficient for the following data.

x 1 11 9 8 5 3 2

y 8 4 6 5 7 7 9

(Do not round the intermediate values. Round your answer to 3 decimal places.)

Correlation coefficient,r=________________

enter the Correlation coefficient rounded to 3 decimal places

#8 (Q)

According to the Air Transport Association of America, the average operating cost of an MD-80 jet airliner is $2,087 per hour. Suppose the operating costs of an MD-80 jet airliner are normally distributed with a standard deviation of $176per hour.

(Round the value of z to 2 decimal places. Round your answers to 2 decimal places.)

(a)At what operating cost would only23% of the operating costs be less?

$___________

enter the dollar amount at which only23% of the operating costs would be less

(b)At what operating cost would 65% of the operating costs be more?

$________________

enter the dollar amount at which 65% of the operating costs would be more

(c)What operating cost would be more than 85% of operating costs?

$______________

enter the dollar amount that would be more than 85% of operating costs

#12 (Q)

Suppose the age distribution in a city is as follows.

Under 18 20%

18-25 16%

26-50 32%

51-65 10%

Over 65 22%

A researcher is conducting proportionate stratified random sampling with a sample size of200. Approximately how many people should he sample from each stratum?

Number of people

Under 18___________________

18-25_____________________

26-50____________________

51-65__________________________

Over 65____________________

Week 4

#11(Q)

Construct 90%, 95%, and 99% confidence intervals to estimatefrom the following data. State the point estimate. Assume the data come from a normally distributed population.

12.7 11.6 11.9 12.7 12.5

11.4 12.0 11.7 11.8 12.7

(Round the intermediate values to 4 decimal places. Round t values to 3 decimal places. Round your answers to 2 decimal places.)

90% confidence interval:______________________________________

enter the lower limit of the 90% confidence interval

95% confidence interval:__________________________________

enter the lower limit of the 95% confidence interval

99% confidence interval:_______________________________________

enter the lower limit of the 99% confidence interval

The point estimate isenter the point estimate __________________

#14 (Q)

Is the environment a major issue with Americans? To answer that question, a researcher conducts a survey of 1255 randomly selected Americans. Suppose695of the sampled people replied that the environment is a major issue with them. Construct a 95% confidence interval to estimate the proportion of Americans who feel that the environment is a major issue with them. What is the point estimate of this proportion?

(Round the intermediate values to 3 decimal places. Round your answer to 3 decimal places.)

_______________________p________________________

enter the lower limit of the confidence interval

enter the upper limit of the confidence interval

The point estimate isenter the point estimate_________________________

Thank you for the assistance