Limit your attention to the most "recent" temperature data, (which we define as years 1990-2013), for NYC. Answer the following questions:
a) For how many years during the recent period, did the annual temperature rise above the historical mean calculated for the entire period? Does this represent a reasonable, relatively large or relatively small percentage of the recent years?
b) Of the 25 warmest years in recorded history, what percentage occurs during the recent period? Do you think the recent period has more or less than its fair share of warmer years?
c) Is the mean temperature for the recent period higher or lower than that of the entire period? Calculate the z-score for the recent mean based on the mean and standard deviation for the entire period. What does the value of the z-score tell you about the difference between the two means?
d) Draw a Box Plot for the recent years and place it next to the Box Plot obtained from the data corresponding to the years prior to 1990. Are there any noteworthy differences between the two?