Question

1)Starting salaries of 50 college graduates who have taken a statistics course have a mean of $44,567. Suppose the distribution of this population is approximately normal and has a standard deviation of $8,606.
Using a 75% confidence level, find both of the following:
(NOTE: Do not use commas or dollar signs in your answers.)

(a) The margin of error: ?

(b) The confidence interval for the mean ?:  <. ?. <

2)A random sample of ?n measurements was selected from a population with standard deviation ?=19.1 and unknown mean ?. Calculate a 95% confidence interval for ? for each of the following situations:

(a) ?=70, ?⎯⎯⎯=101.6

≤?≤

(b)  ?=85, ?⎯⎯⎯=101.6

≤?≤

(c)  ?=105, ?⎯⎯⎯=101.6

≤?≤

3) A statistics practitioner took a random sample of 47 observations from a population whose standard deviation is 35 and computed the sample mean to be 102.

Note: For each confidence interval, enter your answer in the form (LCL, UCL). You must include the parentheses and the comma between the confidence limits.

A. Estimate the population mean with 95% confidence.

Confidence Interval =

B. Estimate the population mean with 90% confidence.

Confidence Interval =

C. Estimate the population mean with 99% confidence.

Confidence Interval =

Answer 1