For items 27-29, refer to the probability distribution below.
27. What is the mean of the probability distribution?
a. 1.5 c.3.5
b. 2.0 d. 4.0
28. What is the variance of the probability distribution?
a. 4.15 c. 8.00
b. 6.35 d. 7.50
29. What is the standard deviation of the probability distribution?
a, 2.38
b. 2.83
C. 3.82
d. 3.28
Answers & Comments
Statistics and Probability
Calculating mean, variance, and standard deviation
27. What is the mean of the probability distribution?
a. 1.5 c.3.5
b. 2.0 d. 4.0
Finding the mean:
Multiply value of the random variable x by the corresponding probability:
X • P(X)
Find the mean by getting sum of X × P(X):
28. What is the variance of the probability distribution?
a. 4.15 c. 8.00
b. 6.35 d. 7.50
Finding the variance:
Multiply the square of the value of the random variable x by its corresponding probability:
Find the sum of the products from above:
Get the variance by subtracting the square of the mean from ΣX² • P(X):
29. What is the standard deviation of the probability distribution?
a, 2.38
b. 2.83
c. 3.82
d. 3.28
Get the square root of the variance to get the standard deviation:
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