Really could use some help with these, the concepts are weird. I don't understand what to do.
A.
In a random sample of 300 adult respondents from the southeastern U.S., the mean cost of the cell phone last purchased was $372.44 with a standard deviation of $116.39. In order to estimate the true mean cost of the last cell phone purchased for the entire population of adults in the southeastern U.S.. we need to build a condence interval round this sample mean (note: assume a 95% Cl unless told otherwise). Using the formula provided in the lecture materials, calculate the 95% Cl around this sample mean. Report the interval with standard formatting (with dollars and cents rounded to hundredths: $XX,X)O(.)O(}: 95% Cl: (lower bound, upper bound} Show relevant work and keep notes on how you did your work so you can compare those to the returned answers you receive after submitting your responses. Question 2 1 pts A recent University of Chicago research project surprised many young adults when it was reported that older Americans (ages 5075) continue to have active sex lives. Specically, it was found that respondents are having sex 2.4 times per week, on average, and deviated from that mean by 0.87. The study was based on interviews with a random sample of 500 older Americans. What is the margin of error (remember, this is the value that we add to and subtract from the sample mean in order to build the interval NOT the interval itself!) at the 90% level of condence? (Round final answer to hundredths.) Show relevant work and keep notes on how you complete your calculation so you can compare it to the answer key. Question 3 1 pts According to the Center for Disease Control, the prevalence of smoking among adults in Oregon is 16.3%. It is 20.5% in Louisiana. In both states, theses estimates are based on samples of 1000 adults. What is the standard error for each state? NOTE: Round to four digits to the right of the decimal and report your answers in the following format: #.#### For Oregon it is l. .. . . | For LOUISIana It lSi l. Question 4 1 pts What is the 95% confidence interval for Oregon and for Louisiana, given the standard errors you just calculated in the previous question? For Oregon, the confidence interval ranges from % to %. For Louisiana, the confidence interval ranges from % to %. Please enter your numbers as whole numbers with decimals, such as "3.5" or "9.2" or "16.0". As the examples here indicate, please include only one digit to the right of the decimal for response to this question and DO NOT include the percent sign. Question 5 1 pts Ben & Jerry are planning for their great ice cream giveaway. They ask a random sample of 200 Vermont residents if they prefer "Cherry Garcia" versus "Chunky Monkey". 75% prefer Chunky Monkey. If they want to be 95% sure of their estimate of this preference for Chunky Monkey, what is the confidence interval they would use to estimate preference for this ice cream in Vermont? The confidence interval is % to Please enter your answers as whole numbers with one digit to the right of the decimal, as described in previous question. Do NOT include the percent sign in your answer.Question 6 0 pts This question is not worth any points. If answered correctly, you will receive an extra credit point added to your score. If answered incorrectly, it will not impact your score at all. A challenge question: Based on your answer, if they expect 2000 people will come tomorrow to their Vermont headquarters for a free scoop of ice cream, what's the upper and lower number of the scoops of Chunky Monkey they should expect to serve those 2000 people? NOTE: do not include commas or decimals in your answers. The lower bound, given our condence interval, is ' scoops. The upper bound, given our confidence interval, is! ' scoops
