Applied statistics
Section 6.2
6.1) Find the margin of error for the given values of c, s, and n.
c=0.8080, s=55, n=21.
6.2) Find the margin of error for the given values of c, s, and n.
c=0.98, s=2.1, n=21.
6.3) Construct the indicated confidence interval for the population mean μ using the t-distribution. Assume the population is normally distributed.
c=0.99, x =13.7 , s=2.0, n=99
The 99% confidence interval using a t-distribution is left parenthesis nothing comma nothing right parenthesis.
6.4) In a random sample of 17people, the mean commute time to work was 31.4 minutes and the standard deviation was 7.3minutes. Assume the population is normally distributed and use a t-distribution to construct a 90% confidence interval for the population mean μ. What is the margin of error of μ? Interpret the results.
6.5) In a random sample of 8 people, the mean commute time to work was 33.5 minutes and the standard deviation was 7.2 minutes. A 90% confidence interval using thet-distribution was calculated to be (28.7,38.3). After researching commute times to work, it was found that the population standard deviation is 9.4minutes. Find the margin of error and construct a 90% confidence interval using the standard normal distribution with the appropriate calculations for a standard deviation that is known. Compare the results.
6.6) The state test scores for 12 randomly selected high school seniors are shown on the right. Complete parts (a) through (c) below. Assume the population is normally distributed.
1428 1222 986
693 720 838
720 741 545
623 1442 942
A) Find the sample mean.
B) Find the standard deviation.
C) A 90% confidence interval for the population mean is ( , ).