9. Which is a probability distribution?
A. The sum of the probabilities of all values of the random variable must
be equal to 1.
B. The sum of the probabilities of all values of the random variable must
be less than 1.
c. The sum of the probabilities of all values of the random variable must
be equal to zero.
D. The sum of the probabilities of all values of the random variable must
be more than 1.
10. What is the mean in tossing 8 coins?
A. 1
B.) 2
C. 4. D. 8​