Had there been no anomaly in the selling patterns of the four, how many pen drives more/less would the four together sell in the year?
Had there been no anomaly, the four would have sold 9300+8310+660+7320=31590 pen drives in a year. But they sell 8460+7365+8980+6720= 31525 drives in the year. Thus they sold 65 drives less. Option b