(d) From April to November in 2021, the manager finds that the mean daily number of mobile phones sold on 48 randomly selected days is 7000 and that the daily number is below 5000 on merely 13 days. Using the data on all 64 days, (i) find the 95% confidence interval for the mean daily number of mobile phones sold, (ii) find the probability that the daily number of mobile phones sold is at least 5000 units, (iii) find the conditional probability that the daily number of mobile phones sold is at least 5000 units given that a day in either February or March is selected, and (iv) Using (d)(ii) and (d)(iii), explain whether the period of time and the daily number of mobile phones sold are independent. (8 marks)