Weekly closing prices of Hewlett-Packard stock from October 1995 to February 1996 are listed below, given in sequential order and rounded to the nearest dollar:
93, 94, 95, 89, 85, 82, 87, 85, 84, 80, 78, 78, 84, 87, 90.
(a) Using time as the horizontal axis and closing price as the vertical axis, construct a trend graph showing how the price moved during this period.
(b) Construct a stem and leaf plot.
(c) Calculate the mean and median closing price.
(d) Use the change of scale procedure in Section 1.5 to calculate the standard deviation of the closing price.