An unbiased coin is tossed 4 times. Find the mean and variance of the number of heads obtained.

Given:


n=4


p(getting atleast one head)=?


• 0 head : HHHH


• 1 head : HTTT


THTT


TTHT


TTTH


• 2 heads :HHTT


HTHT


HTTH


THHT


THTH


TTHH


• 3 heads: HHHT


HHTH


HTHH


THHH


• 4 heads : HHHH


Total outcomes = 16


Outcomes containing at least 1 head = 15


P(getting at least 1 head)=


1