Assume a telephone company has created a dataset for a representative sample of its customers. The following are descriptive statistics for a variable that captures the daytime phone usage (in minutes) for each customer.

Analysis Variable : DayMinutes
Mean	Std Dev	Std Error	Variance	Minimum	Maximum	N	Lower Quartile	Median	Upper Quartile
180.55	54.48	0.92	2967.62	0.47	351.46	3500	144.19	180.32	217.26

a) What is the 50^th percentile?

b) If the data is assumed to be normally distributed, what would be the range of values within two standard deviation of the mean? Approximately, how many customers would have daytime usage minutes that fall within this range?

c) What is the interquartile range

d) Assume all the statistics (shown above) remain the same with the exception of N. If N is changed to 4225, what would be the Standard Error?