EE304 Probability and Statistics – Tutorial 1 Solutions
Question 1
A fair coin is tossed three times. What is the probability of getting:
(i) exactly two heads?
Solution:
There are a total of 2×2×2 = 8 possible outcomes. The outcomes cor-
responding to exactly 2 heads are HHT, HT H, T HH. So the desired
probability is 3
8.
(ii) exactly 1 tail?
Solution:
This is again equal to 3
8as getting exactly 1 tail means that we have
exactly two heads!
(iii) at least 1 tail?
Solution:
The only way we will not get at least 1 tail is if we get 3 heads. Thus
the desired probability is
1−1
