The number of credit cards carried by students can be modelled using the Poisson distribution. A sample of students generated the following data credits cards X 0 1 2 3 4 5 6 students with X credit cards 42 244 358 96 32 8 2 Find the sample size n, and hence the sample mean ¯X . Use this information to calculate a 95% confidence interval for the average number of credit cards carried by students.