The mean and standard deviation of `1,2,3,4,5,6` are

If the mean and standard deviation of 5,3,7,a,b are 5 and 2 respectively, then a and b are roots of equation.

The mean and standard deviation for a,b and 2 are 3 and 1 respectively,then value of ab is

The mean and standard deviation of 6 observations are 8 and 4 respectively . If each observation is multiplied by 2, find the new mean and new standard deviation of the resulting observation.

The mean and standrad deviation of 100 items are 50, 5 and that of 150 items are 40, 6 respectively. What is the combined standard deviation of all 250 items?

The mean and standard deviation of random variable X are 10 and 5 respectively, then E((X-15)/5)^(2) = ________.

The mean and standard deviation of 18 observations are found to be 7 and 4 respectively. On rechecking it was found that an observation 12 was misread as 21. Calculate the correct mean and standard deviation.

The mean and standard deviation of a binomial variate X are 4 and 3 respectively. Then, P(Xge1) is equal to