3.1. Discrete Random Variables http://www.ck12.org
If our first toss were a tails...
Therefore there are 16 possible outcomes:
HHHH,HHHT,HHTH,HHTT,HTHH,HTHT,HTTH,HTTT,THHH,
THHT,THTH,THTT,TTHH,TTHT,TTTH,TTTT
P(1 head) =4
16
P(1 head) =1
4
Alternate Solution:
We have one coin and want to find the probability of getting one head in four tosses. We need to calculate two parts
to solve the probability problem.
Numerator (Top)
In our example, we want to have 1 H and 3 Ts. Our favorable outcomes would be any combination of HTTT. The
number of favorable choices would be: