10.7 You measure 37 turtles' weights, and find they have a mean weight of 47 ounces. Assume the population standard deviation is 11.2 ounces. Based on this, what is the maximal margin of error associated with a 90% confidence interval for the true population mean turtle weight. Give your answer as a decimal, to two places

______ounces

10.8 You measure 29 randomly selected textbooks' weights, and find they have a mean weight of 32 ounces. Assume the population standard deviation is 4.6 ounces. Based on this, construct a 90% confidence interval for the true population mean textbook weight.

Give your answers as decimals, to two places

______< < _______

10.9 A scientific study was conducted to determine the hours of sleep that college students get per night. The study surveyed 30 college students and obtained the following data:

8.6, 8.1, 8.7, 8, 8, 8.4, 9.4, 8.9, 8.3, 8.4, 7.9, 8.3, 8.5, 9.8, 8.5, 8.5, 7.4, 8.5, 8.3, 8.3, 8.6, 8.4, 8.7, 8.2, 8.4, 8.4, 8.9, 8.2, 8.3, 8.2

Assuming the population standard deviation is =0.49=0.49, construct a 85% confidence interval for the average hours of sleep per night that college students get.

x=____

2=_____

z2=______

Margin of Error: E=_______

We are 85% confident that college students get an average of between ________hours and ______hours of sleep per night.

11.2 A researcher is interested in finding a 90% confidence interval for the mean number of times per day that college students text. The study included 135 students who averaged 29.1 texts per day. The standard deviation was 17.2 texts. Round answers to 3 decimal places where possible. a. To compute the confidence interval use a ? z ? or t ? distribution. b. With 90% confidence the population mean number of texts per day is between ____and _____ texts. c. If many groups of 135 randomly selected members are studied, then a different confidence interval would be produced from each group. About _____ percent of these confidence intervals will contain the true population number of texts per day and about _______percent will not contain the true population mean number of texts per day.