6. In a study of the length of time it takes students to earn a bachelor's degree. 80 students are randomly selected, and they are found to have a mean of 4.8 years with a standard deviation of 1.9 years. Joe wishes to construct a 95% confidence interval for the mean amount of time students need to complete their bachelor's degree. Help Joe by nding the following information. (Note: you do not have to construct the condence interval...just fill in the blanks below.) a) n= b)s= c) x: d) Level of confidence (as a decimal): 7. A marketing manager for a cell phone company would like to know how many children aged 10-11 have cell phones. In a prior survey it was found that 35% of children aged 10-11 had cell phones. What sample size should the marketing manager obtain if she wishes her estimate to be within 4.2 percentage points with 99% confidence? (Note: you do not have to solve for the sample size...just fill in the blanks below.) a) E = b) p\" = c) Level of confidence (as a decimal): d) What is the goal of the