The mean annual percentage change

  A Mathematics Investment analyst receives the following data showing the percentage changes in Labor costs of Junior managers in an investment bank Chain over a 12-months period. The highest change observed was +172 per cent for a senior manager in one of the banks in Madrid. Percentage Change -5 to under 0 Frequency 2 Percentage Change 0 to under 5 Frequency 32 Percentage Change 5 to under 10 Frequency 25 Percentage Change 10 to under 15 Frequency 10 Percentage Change 15 to under 20 Frequency 8 Percentage Change 20 to under 25 Frequency 3 Percentage Change 25 to under 30 Frequency 2 Percentage Change 30 to under 35 Frequency 5 Percentage Change 35 to under 40 Frequency 4 Percentage Change 40 to under 100 Frequency 3 Percentage Change 100 to 172 Frequency 4 a). What is the mean annual percentage change in Labor costs for Junior managers in this investment bank? b). What is the estimate of the Median Value? c). What is the modal class interval?