The number of centuries scored in a year by seven randomly selected batsmen are: 3, 5, 6, 3, 7, 6, 4 Find the variance and standard deviation of these seven batsmen.

What is the mean of 1, 2, 3, 4, 5, 6, 7 ?

A box contains 6 pens , 2 of which are defective Two pens are taken randomly from the bax . If r,v. X. : Number of defective pens obtained , then standard deviation of x=

Find the mean of the following data : Goals scored in 10 matches : 2, 2, 3, 5, 4, 2, 1, 3, 3, 4, 3

Find the number of distinct numbers formed using the digits 3, 4, 5, 6, 7, 8, 9, so that odd positions are occupied by odd digits.