Shopkeeper wants to maximise profit, so he will choose that size which used to sell most.
Mean is better option for an invigilator to bring sufficient number of additional papers.
Mean gives the idea of number of additional/Supplementary paper for exam,from analysis he/she can judge the average number of additional sheet requirements.
Mean is better option. Laddo should be in average quantity so that it will not get waste.
Mode will be better option. Mode will give name of cricketer who is loved by at most number of students.