In any discrete series (when all the valuenot same) the relationship betweemean and S.D. is

In any discrete series (when all values are not same ) is x represents mean deviation about mean and y represents standard deviation, then which one of the following is correct?

Is the result obtained by all the three methods the same when finding the mean ?

When a resistance R is connected in series with an element A, the electric current is found to be lagging behind the voltage by angle theta_(1) . When the same resistanceis connected in series with element B, current leads voltage by theta_(2) . When R, A, B are connected in series, the current now leads voltage by theta. Assume same AC source is used in all cases, then:

When a resistance R is connected in series with an element A, the electric current is found to be lagging behind the voltage by angle theta_(1) . When the same resistanceis connected in series with element B, current leads voltage by theta_(2) . When R, A, B are connected in series, the current now leads voltage by theta. Assume same AC source is used in all cases, then:

Name the physical quantity which is same different in all bulbs when three bulbs are of same wattage are connected on series.

The probability distribution of a discrete random varible X is as follows: Find the expectation and S.D. of .X.

In which of the following series all the elements are radioactive in nature Lanthanides,Actinides,d-block elements,s-block elements