513. Find the mean, variance and standard deviation using short-cut method.

The runs scored by two batsmen in 10 innings are: A: 65, 58, 68, 44, 48, 45, 60, 62, 60, 50
B: 48, 80, 58, 44, 52.65, 73, 56, 64.50.
Which of the batsmen is more consistent and which one is more variable?

The marks obtained (out of 100) by two students in 10 qualifying tests were: A: 48, 53, 58, 41, 54, 52, 54, 49, 51, 50
B: 11, 98, 60, 94, 48, 52,17, 90, 20, 20
Who is more consistent in performance and who is more variable?

The mean and standard deviation of marks obtained by 50 students of a class in three subjects, Mathematics, Physics and Chemistry are given below:

Subject               Mathematics                Physics                Chemistry
Mean                      42                               32                         40.9

Standard 
deviation                12                                15                          20
which of the three subjects shows the highest variability in marks and which shows the lowest?

An analysis of monthly wages paid to workers in two firms A and B, belonging to the same industry, gives the following results:
                                                                                    Firm A                        Firm B
No. of wage earners                                                         586                            648
Mean of monthly wages                                                 Rs 5253                     Rs 5253
Variance of the distribution of wages                                   100                            121

(i) Which firm A or B pays larger amount as monthly wages?
(ii) Which firm A or B shows greater variability in individual wages?