In Q No. 2, We have considered 4 bins of equal size. Therefore in each bin we will be having 5 objects.
Comparison in a single bin will be = (5 * 4)/2 = 10
Therefore comparisons in 4 bins = 4*10 = 40
Q no 4 is the continuation of question 1 and 3. If you properly understood 1 and 3, we are having 190 comparisons in q no 1 and 10 comparions in Q no 3. Therefore the factor at which comparisons reduced is 190/10 = 19
Regards,
Nijin
IITM Online Degree Programme.