Answer Happy

For #1-10, use formulas/tables. Label and show inputs to formulas. For problems 11-17, use calculator functions where possible, writing functions on lab. Rounding sample proportion & margin of error-4 decimal pos, CI limits for proportion-3 dec. pos, Cl limits for mean-1 dec. pos, percents-i dec. pos. To help you with this lah, a sample of a "formulas and tables" lab and a "calculator function" lab are posted in the instructional materials, each with steps and complete solutions! Each problem on this lab is worth 6 points except where otherwise stated. 1) How many women must be randomly selected to estimate the mean weight of women in one age group. We want 90% confidence that the sample mean is within 3.2 lb of the population mean, and the population standard deviation is known to be 16 lb. Hint: Use formula for sample size determination. 2) In a random sample of 170 college students, 112 had part-time jobs. Find the margin of error for the 95% confidence interval used to estimate the population proportion. I 3) Of 203 employees selected randomly from one company, 20.69% of them commute by carpooling. a) Construct a 99% confidence interval for the true percentage of all employees of the company who carpool. b) Write a statement describing your results. Hint: Review the statements in the example labs that are posted! 4) A random sample of 98 light bulbs had a mean life of x = 594 hours, and a is known to be 38 hours. a) Construct a 90% confidence interval for the mean life, μ, of all light bulbs of this type. b) Write a statement describing your findings. Include all four necessary elements. 5) (8 points) Of 142 randomly selected adults, 33 were found to have high blood pressure. a) Construct a 95% confidence interval for the true percentage of all adults that have high blood pressure. TE b

5) (8 points) Of 142 randomly selected adults, 33 were found to have high blood pressure. a) Construct a 95% confidence interval for the true percentage of all adults that have high blood pressure. b) Would it be accurate to say that at least 25% of all adults have high blood pressure? (yes or ) Hint: The next two questions are asking you to find minimum sample size to estimate population proportion. Make sure to use the appropriate formula for each. Ask yourself: Is the sample proportion provided? 6) A newspaper article about the results of a poll states: "In theory, we should be 99% confident that the results of such a poll should differ by no more than 3 percentage points in either direction from what would have been obtained by interviewing all voters in the United States." Find the sample size suggested by this statement. 7) The CEO of Computers, Inc., wants to estimate the proportion of U.S. families that have at least one laptop computer. From last year's study, it was determined that 74% have a laptop. What minimum sample size is required if the CEO wants no more than a 3.5% margin of error and wants the estimate to be 90% accurate. 8) Express the confidence interval (0.556, 0.706) in the form of p t E.

8) Express the confidence interval (0.556, 0.706) in the form of p + E. 9) The amounts (in ounces) of juice in eight randomly selected juice bottles are: 15.2 15.0 15.3 15.1 15.8 15.3 15.4 15.7 a) Construct a 98% confidence interval for the mean amount of juice in all such bottles. Assume the population of values has a normal distribution. You may obtain the sample mean and standard deviation from 1- VarStats b) Write a statement describing your results. Include all four necessary elements. 10) Find the critical value Zex/2 that corresponds to a 98% confidence level. Choose correct answer. B) 2.33 A) 2.575 C) 2.05 D) 1.75 Begin using calculator functions (where possible) here. Write calculator function used and any inputs before answering, 11) Of 380 randomly selected medical students, 21 said that they planned to work in a rural community. Choose the 95% confidence interval for the true proportion of all medical students who plan to work in a rural community. A) 0.0280 p<0.0826 B) 0.0360p<0.0745 D) 0.0251<p <0.0854 C) 0.0323<p<0.0782