<PRE><B>Question 1132196</B>
There are 8 events in the sample space
:
HHH, HHT, HTH, HTT, THH, THT, TTH, TTT
:
Probability(P) (0 heads) = 1/8
:
P(1 head) = 3/8
:
P(2 heads) = 3/8
:
P(3 heads) = 1/8 
:
(a) 0 heads p(0) = 1/8 = 0.125, 1 head p(1) = 3/8 = 0.375, 2 heads p(2) = 3/8 = 0.375, 3 heads p(3) = 1/8 = 0.125
:
x   p(x)
---------
0   0.125
1   0.375
2   0.375
3   0.125
:
(b) mean(u) = (0 +1 +2 +3)/4 = 1.5
:
variance = ( (0-1.5)^2 +(1-1.5)^2 +(2-1.5)^2 +(3-1.5)^2 )/4 = 1.25
:
standard deviation = square root(variance) = square root(1.25) = 1.118
:
</PRE>