1. A researcher is interested in finding a 98% confidence interval for the mean number of times per day that college students text. The study included 112 students who averaged 42.7 texts per day. The standard deviation was 24.9 texts. Round answers to 3 decimal places where possible.

a. To compute the confidence interval use a ? z t distribution.

b. With98% confidence the population mean number of texts per day is between_____ and _____ texts.

c.If many groups of 112 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.

2. If n=8n=8, xx=36, and s=9s=9, construct a confidence interval at a 98% confidence level. Give your answers to one decimal place.

________ < <_________

3. Express the confidence interval (26.1%,32.3%)(26.1%,32.3%) in the form of p^E. ______% ______%

4. A Gallup survey based on telephone and face-to-face interviews with 4,220 adults in China, aged 15 and older suggests that 30% smoke regularly or occasionally. The following is also noted "one can say with 95% confidence that the maximum margin of sampling error is 2.4 percentage points". Which of the following is true based on the results of this survey?

• We are 95% confident that 25.2% to 34.8% of all Chinese adults smoke.
• We are 95% confident that 27.6 % to 32.4 % of all Chinese adults smoke.
• If the sample size was larger, the margin of error would be larger as well.
• If we were to randomly sample another group of 4,220 Chinese adults we would find that exactly 30% of them smoke as well.
• Exactly 30% of all Chinese adults smoke.