planning value = (45000-30000)/4 = 15000/4 = 3750
a. $500?
n = (Za/2* σ/E)^2
n = (1.96* 3750/500)^2
n = 217
b. $200?
n = (Za/2* σ/E)^2
n = (1.96*3750/200)^2
n = 1351
c. $100?
n = (Za/2* σ/E)^2
n = (1.96* 3750/100)^2
n = 5403
Annual starting salaries for college graduates with degrees in business administration are generally expected to be between $30,000 and $45,000. Assume that a 95% confidence interval estimate of the population mean annual starting salary is desired. What is the planning value for the population standard deviation (to the nearest whole number)?
How large a sample should be taken if the desired margin of error is as shown below (to the nearest whole number)?
a. $500?
b. $200?
c. $100?
6 answers
How planning value is calculated and where the 4 come from?
A Phoenix Wealth Management/Harris Interactive survey of 1500 individuals with net worth of $1 million or more provided a variety of statistics on wealthy people (BusinessWeek, September 22, 2003). The previous three-year period had been bad for the stock market, which motivated some of the questions asked.
a. The survey reported that 53% of the respondents lost 25% or more of their portfolio value over the past three years. Develop a 95% confidence interval for the proportion of wealthy people who lost 25% or more of their portfolio value over the past three years. (to 3 decimals)
a. The survey reported that 53% of the respondents lost 25% or more of their portfolio value over the past three years. Develop a 95% confidence interval for the proportion of wealthy people who lost 25% or more of their portfolio value over the past three years. (to 3 decimals)
You use 4 as a 'best guess' when you don't have a previous study's standard deviation or haven't used a pilot study's standard deviation. It is a widely accepted rule in Statistics when the first two options are not available.
the 4 comes from the standard deviation being exactly 1/4 of the range.
What is the planning value for the population standard deviation (to the nearest whole number)?
3750
How large a sample should be taken if the desired margin of error is as shown below (to the nearest whole number)?
a. $500?
216
b. $200?
1351
c. $100?
5403
d. Would you recommend trying to obtain the $100 margin of error?
No, sample requires too much time and expense
3750
How large a sample should be taken if the desired margin of error is as shown below (to the nearest whole number)?
a. $500?
216
b. $200?
1351
c. $100?
5403
d. Would you recommend trying to obtain the $100 margin of error?
No, sample requires too much time and expense
3 answers