Question 601688
A coin is tossed three times 
Binomial Problems with n = 3 and p(tail) = 1/2
-------------------------------------

find the probability that 

.exactly one tail turns up
P(x = 1) = 3C1(1/2)(1/2)^2 = 3/8
--------------------------------- 
.at least two tail turn up
P(x = 2 or x = 3) = 3C2(1/2)^2(1/2) + 3C3(1/2)^3*(1/2)^0
= 3/8 + 1/8 = 4/8 = 1/2
============================= 
.no tail turn up.
P(x = 0) = 3C0(1/2)^0*(1/2)^3 = 1/8
---------------------------------------
Cheers,
Stan H.