- #1
kent davidge
- 933
- 56
Homework Statement
A coin is thrown 8 times. What's the probability for obtaining
a) 5 heads
b) at least 1 head
c) at most 2 heads
Homework Equations
Bayer's rule, I think.
The Attempt at a Solution
Using Bayer's rule:
a) ##P(5 \text{he}, 3 \text{ta}) = P(5 \text{he} | 3 \text{ta}) P(3 \text{ta}) = (1/2)^5 (1/2)^3 = (1/2)^8##;
b) ##\sum_{i=1}^{8} P(i \text{he}, (8-i) \text{ta}) = \sum_{i=1}^{8} P(i \text{he} | (8-i) \text{ta}) P((8-i) \text{ta}) = \sum_{i=1}^{8} (1/2)^i (1/2)^{8-i} = 8(1/2)^8##.
c) ##\sum_{i=0}^{2} P(i \text{he}, (8 - i) \text{ta}) = 3 (1/2)^8##.
Is this correct?