Find the mean and standard deviation of each of the following probability distributions:

Mean of any probability distribution is given by Mean = ∑xipi


Standard Deviation is given by SD = √Variance where variance is given by:


Variance = ∑ xi2pi – (∑xipi)2


first we need to find the products i.e. pixi and pixi2 and add them to get mean and apply the above formula to get the variance.


Following table gives the required products :



mean = 0.4+0.6+0.6+0.4 = 2.0


And variance = 0.4 +1.2 + 1.8 + 1.6– (2)2 = 1.0


Standard deviation = √1 = 1


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