An online used car company sells second-hand cars. For 30 randomly selected transactions, the mean price is 2900 dollars. Part a) Assuming a population standard deviation transaction prices of 230 dollars, obtain a 99% confidence interval for the mean price of all transactions. Confidence interval: ( Part b) Which of the following is the correct interpretation for your answer in part (a)? OA. We can be 99% confident that the mean price for this sample of 30 transactions lies in the interval O B. There is a 99% chance that the mean price of all transactions lies in the interval C. If we repeat the study many times, 99% of the calculated confidence intervals will contain the mean price of all transactions. O D. None of the above

Use the data attached: 1. In two to three sentences, explain what a confidence interval means(in general), as if you were talking to someone who has not taken statistics. 2. In one to two sentences, explain what this confidence interval means for this particular study.

A survey was conducted where 27 students were asked which social media app is their favorite, Twitter or Tiktok.    male female twitter 4 4 TikTok 4 15  create and interpret (in context) a one-proportion confidence interval. You may choose the level of confidence. conduct a Chi-Squared test for Association to determine if your data provide statistically significant evidence of an association between your two variables.

A Surprising fact indicates that a small proportion of teens use a password on their mobile device. A poll chooses a simple random sample of 120 teens and asks if they use a password on their mobile device. The results showed that 56 of teens in our  sample used a password on their mobile device. Find a 90 % confidence interval for the proportion of teens who use a password on their mobile device. Interpret your confidence interval.

4. on paper.  random sample of 130 human body temperatures had a mean 98.25 degree and astandard deviation of 0.73 degree. Construct a 99% confidence interval for the average body temperature ofhealthy people.

Use R Studio to answer the following question:

Which type of confidence interval should you use in this situation? A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year with a standard deviation of 23.8 days. The distribution is approximately normally distributed. Find the 90% confidence interval for the average days worked of all payroll departments.   Question 2 options:   1)  a confidence interval for the mean using a table value from the standard normal distribution.   2)  a confidence interval for the mean using a table value from the t distribution.   3)  a confidence interval for a proportion using a table value from the standard normal distribution.   4)  a confidence interval for proportion using a table value from the t distribution.   5)  none of the above.

Suppose a sample of 9 customers spends an average of $200 with a standard deviation $20 what is a 95% confidence interval for the sample mean. Use the fact that 95% of sample means are within 2.306 standard errors of the sample mean.

A surprising fact indicates that a small proportion of teens use a password on their mobile device. A poll chooses a simple random sample of 120 teens and asks if they use a password on their mobile device. The results showed that 56 of teens in our sample used a password on their mobile device. Find a 90 % confidence interval for the proportion of teens who use a password on their mobile device. Interpret your confidence interval.