Christina wants to know the true average number of pages in a typical textbook. She randomly selects 196 books, and they have an average of 161 pages. Calculate a 90.3% confidence interval if you are given that the standard deviation for a single book is 75 pages.

An environmental researcher took 30 water samples from different areas of a lake. He measured the pH level of each water sample. The standard deviation for the 30 pH levels was about 1.4.What is the best interpretation of the standard deviation? The pH level of a typical water sample was about 1.4 units from the mean on average. The difference between the minimum and maximum pH levels was about 1.4 units. The entire lake had a pH level that was about 1.4 units. The pH level of any given water sample was about 1.4 units from the mean. - this one is wrong

A particular fruit's weights are normally distributed, with a mean of 777 grams and a standard deviation of 9 grams.The heaviest 10% of fruits weigh more than how many grams?Give your answer to the nearest gram.

A person in the U.S. eats about 25 pounds of M&M's per year with a standard deviation of 3 pounds. How many M&M's would I have to eat to be in the 3rd quartile?

You went to rent an unfurnished one-bedroom apartment in Boston next year. The mean monthly rent for a simple random sample of 32 apartments advertised in the local newspaper is $1,400. Assume that the standard deviation is known to be $220. Find a 99% confidence interval for the mean monthly rent for unfurnished one bedroom apartments available for rent in this community.

There is a new medication for diabetes, fifteen participants take the medication for fifteen days. The average blood glucose before taking the medication was 155 (population mean). The average blood glucose after taking the medication is 110. The standard deviation for the average glucose after taking the medication is 4.6. You want to evaluate if there is statistical evidence that there is a reduction in the mean glucose after taking the medication for 15 days. You must conduct a t-test. What is the t-statistic?