Answers to quiz 4

Round all numbers that aren’t whole numbers except proportions to two places after the decimal.
Round proportions to four places after the decimal, like the number in the z-score tables.

(14 points)
Sample of 20 pulse rates for women:
97, 88, 83, 77, 60, 78, 73, 67, 72, 82, 70, 67, 60, 80, 90, 100, 69, 80, 60, 68

n = 20 x-bar = 76.05 sx = 11.66


median = __75___ z(median) = ___-.05___ Test okay? __yes___


Proportion for z(high) = _.9798_ Proportion for z(low) = _.0838_
Test okay? __yes___


If both tests are okay, continue to the 95% confidence interval for µx.
CLM95% = _2.093___


From this sample, we are 95% confident the true average µx of women’s pulse rates is between 70.59 and 81.51.

Finding the confidence interval for sigmax using df = n – 1 and sx is sx*sqrt((n-1)/chi-squareleft) > sigmax > sx*sqrt((n-1)/chi-squareright)
(6 points)
For this sample find the endpoints for 95% confidence.

chi-squareleft= _8.907__ chi-squareright = __32.852__


We are 95% confident given this sample that the true standard deviation of the population of women’s pulse rates is between _8.87__ and __17.03__.