Week 3 - 5 questions

Question 1.

In a recent year, the average daily circulation of theWall Street Journalwas2,276,207. Suppose the standard deviation is 70,940. Assume the paper's daily circulation is normally distributed.

(a)On what percentage of days would circulation pass1,803,000?

(b)Suppose the paper cannot support the fixed expenses of a full-production setup if the circulation drops below1,631,000. If the probability of this even occurring is low, the production manager might try to keep the full crew in place and not disrupt operations. How often will this even happen, based on this historical information?

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

(a)P(x>1,803,000) =

enter the probability that the daily circulation would pass1,803,000

(b)P(x<1,631,000) =

enter the probability that the daily circulation will drop below1,631,000

Question 2.

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 $163per 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

Question 3.

Suppose the age distribution in a city is as follows.

Under 18 26%

18-25 18%

26-50 32%

51-65 8%

Over 65 16%

A researcher is conducting proportionate stratified random sampling with a sample size of350. Approximately how many people should he sample from each stratum?

Number of people

Under 18 __________

18-25__________

26-50_________

51-65___________

Over 65_____________

Question 4.

The Aluminum Association reports that the average American uses 56.8 pounds of aluminum in a year. A random sample of50households is monitored for one year to determine aluminum usage. If the population standard deviation of annual usage is12.1pounds, what is the probability that the sample mean will be each of the following?

a.More than58pounds

b.More than57pounds

c.Between56and58pounds

d.Less than54pounds

e.Less than48pounds

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

a.enter the probability that the sample mean will bemore than58pounds __________

b.enter the probability that the sample mean will be more than57pounds _________

c.enter the probability that the sample mean will be between56and58pounds ____________

d.enter the probability that the sample mean will be less than54pounds _____________

e.enter the probability that the sample mean will be less than48pounds ______________

Question 5.

A survey of 2645 consumers by DDB Needham Worldwide of Chicago for public relations agency Porter/Novelli showed that how a company handles a crisis when at fault is one of the top influences in consumer buying decisions, with 73% claiming it is an influence. Quality of product was the number one influence, with 96% of consumers stating that quality influences their buying decisions. How a company handles complaints was number two, with 85% of consumers reporting it as an influence in their buying decisions. Suppose a random sample of1,200consumers is taken and each is asked which of these three factors influence their buying decisions.

a.What is the probability that more than910consumers claim that how a company handles a crisis when at fault is an influence in their buying decisions?

b.What is the probability that fewer than1,125consumers claim that quality of product is an influence in their buying decisions?

c.What is the probability that between82% and84% of consumers claim that how a company handles complaints is an influence in their buying decisions?

*(Round the values of z to 2 decimal places. Round the intermediate values to 4 decimal places. Round your answer to 4 decimal places.)

**(Round the values of z to 2 decimal places. Round the intermediate values to 4 decimal places. Round your answer to 5 decimal places.)

a.enter the probabilitythat more than910consumers claim their buying decisions are influenced by how a company handles a crisis when at fault rounded to 4 decimal places ---Answer 0.0136

b.enter the probabilitythat fewer than1,125consumers claim that quality of product influences their buying decisions rounded to 5 decimal places

----Answer 0.00003

c.enter the probabilitythat between82% and84% of consumers claim that their buying decisions are influenced by how a company handles a crisis when at fault rounded to 4 decimal places ______________________