The Cleaning Institute conducted a survey in 2009 of 865 adults asking each adult the number of times they wash their hands per day. The mean number of times those sampled washed their hands was 8.726 with a standard deviation of 6.611. Researchers would like to include a 90% confidence interval. • How many degrees of freedom would be associated with the t-distribution? df = • With 90% confidence, we estimate the mean number of times an individual washes their hands is between • Based on the interval computed, can we conclude the typical American adult washes their hands fewer than 9 times per day, on average? and - (The appropriate t critical point is t = 1.647. Round the limits of your interval to 4 decimal places.) Yes. Most of the interval falls below 9. No. The interval extends above 9. Yes. The interval falls entirely below 9.

The patient recovery time from a particular surgical procedure was normally distributed with a mean of 5.6 days and a standard deviation of 2.1 days.  What is the probability of spending more than three days in recovery? The 90th percentile for recovery time is?

An SRS of 29 students at HCC gave an average height of 5.5 feet and a standard deviation of .1 feet. Construct a 90% confidence interval for the mean height of students at HCC.

Bone mineral density (BMD) is a measure of bone strength. Studies show that BMD declines after age 45. The impact of exercise may increase BMD. A random sample of 59 women between the ages of 41 and 45 with no major health problems were studied. The women were classified into one of two groups based upon their level of exercise activity: walking women and sedentary women. The 39 women who walked regularly had a mean BMD of 5.96 with a standard deviation of 1.22. The 20 women who are sedentary had a mean BMD of 4.41 with a standard deviation of 1.02. Which of the following inference procedures could be used to estimate the difference in the mean BMD for these two types of women