A recent survey of randomly selected children who wear braces on their teeth, conducted by the American Board of Orthodontics4 , revealed that the 95% confidence interval for the average number of months that children wore braces was between 20 and 23 months. The study also noted that the standard deviation of the number of months surveyed was six months. Please answer the questions that follow as they relate to this study: a. (5 points) How do i create an interval estimate for the true (population) mean number of months that children wear braces allowing for a total estimation error of 12%.

b. (5 points) My orthodontist informed me that once he applied braces to my child's teeth, she would need to wear them no longer than 22 months. How likely is it that she will actually need to wear them longer than this? (Note that it is well-known that most people end up having to wear braces longer than initially estimated.)

Also there is no sample size indicated can this truly be solved How do i first find the sample size is there a formula