Second, the researcher wishes to use graphical descriptive methods to present summaries of the data on each of the two variables: hours worked per week and yearly income, as stored in file HOURSWORKED.xls. a) The number of observations (n) is 65 individuals. The researcher suggests using 7 class intervals to construct a histogram for each variable. Explain how the researcher would have decided on the number of class intervals (K) as 7. (2 marks) b) The researcher suggests using class intervals as 10 < X 15, 15 < X 20, ..., 40 < X 45 for the hours per week variable and class intervals 40 < X 45, 45 < X 50, ..., 70 < X 75 for the yearly income variable. Explain how the researcher would have decided the width of the above class intervals (or class width). (2 marks) c) Draw and display a histogram for each of the two variables using appropriate BIN values from part (b) and comment on the shape of the two distributions.