Find the mean deviation about the mean for the data in exercises 9 and 10.
9. Income per day in ₹: 0-100, 100-200, 200-300, 300-400, 400-500, 500-600, 600-700, 700-800
Number of days: 4, 8, 9, 10, 7, 5, 4, 3
a) 175
b) 225
c) 275
d) 325