According to Statistical Abstract of the United States, 2012, average salary (in dollars) of primary and secondary school classroom teachers in 2009 in the United States varied among states with a five number summary of: minimum = 35,070, Q1 = 45,840, median = 48,630, Q3 = 55,820, maximum = 69,119. (Data available in the teacher_salary file.)
a. Find and interpret the range and interquartile range.
b. Sketch a box plot, marking the five-number summary on it.
c. Predict the direction of skew for this distribution. Explain.
d. If the distribution, although skewed, is approximately bell shaped, which of the following would be the most realistic value for the standard deviation: 

(i) 100,

(ii) 1000, 

(iii) 7000, 

(iv) 25,000? Explain your reasoning.