In: Statistics and Probability
P(H)=2/3,P(T)=1/3, a coin is thrown 3times,X is a random variable that shows the number of getting head
a) find the distribution of X
b)find the expected value of X
c) find the variannce of X
d)find the standard deviation of X
Solution:
Given:
P(H)=2/3
P(T)=1/3
n= number of times a coin is tossed =3
X = number of times getting head
Part a)
The distribution of X:
Since number of trials are fixed and are independent with probability of success = probability of getting head is fixed or constant for each trial, the distribution of X = number of times getting head follows Binomial distribution with parameters n=3 and p=2/3.
Part b)
Expected value of X is:
Part c)
The variance of X is
Part d)
The standard deviation of X