Question

A fair coin is flipped 10 times. What is the probability that exactly 4 of the 10 flips come up heads

Answer 1

P = 0.205 (20.5%)

Explanation:

`f(x)=(10nCr4)(.5)^(4) (.5)^(6) =(210)(0.0625)(0.015625)=0.205`

Hope this helps

Answer 2

105/2^9

Explanation:

The probability of getting a head in a single toss

p=12

The probability of not getting a head in a single toss

q=1−12=12

Now, using Binomial theorem of probability,

The probability of getting exactly r=4 heads in total n=10 tosses

=10C4(1/2)4(1/2)10−4

=10×9×8×7/4! 1/2^4 1/2^6

=2^44⋅9⋅35/24(2^10)

=105/2^9