An article in the Journal of Database Management ["Experimental Study of a Self-Tuning Algorithm for DBMS Buffer Pools (2005, Vol. 16, pp. 1-20)] provided the workload used in the TPC-C OLTP (Transaction Processing Performance Council's Version C On-Line Transaction Processing) bench- mark, which simulates a typical order entry application. The frequency of each type of transaction (in the second col- umn) can be used as the percentage of each type of transac tion. The average number of selects operations required for each type transaction is shown.

(a) Determine the mean and standard deviation of the number of selects operations for a transaction from the distribution of types shown in the table.

(b) Determine the mean and standard deviation of the total number of operations (selects, updates.....and jodes) for a transaction from the distribution of types shown in the table.