hey guys, i think this might have been addressed below but when you get a question as the one below…how do you know when to use the std error as opposed to the std deviation? The average salary for a sample of 61 CFA charterholders with 10 years experience is $200,000, and the sample standard deviation is $80,000. Assume the population is normally distributed. Which of the following is a 99 percent confidence interval for the population mean salary of CFA charterholders with 10 years of experience? A) $160,000 to $240,000. B) $197,811 to $202,189. C) $172,754 to $227,246. D) $172,514 to $227,486. Answer is C using a t statistic and the std error.

all you need to know is look at the student t distribution table, look for 60( which is the closest to 61), look for 0.005, and you will get 2.660. 200000+or- 2.660*(80000/(61^(1/2))

rehman99 Wrote: ------------------------------------------------------- > hey guys, i think this might have been addressed > below but when you get a question as the one > below…how do you know when to use the std error > as opposed to the std deviation? > > The average salary for a sample of 61 CFA > charterholders with 10 years experience is > $200,000, and the sample standard deviation is > $80,000. Assume the population is normally > distributed. Which of the following is a 99 > percent confidence interval for the population > mean salary of CFA charterholders with 10 years of > experience? > > A) $160,000 to $240,000. > B) $197,811 to $202,189. > C) $172,754 to $227,246. > D) $172,514 to $227,486. > > Answer is C using a t statistic and the std error. use the standard error when they are talking about a sample, like in this example here.