Which of the following is always true for all probability density functions of continuous random variables?
A. They have the same height
B. They are bell-shaped
C. They are symmetrical
D. The area under the curve is 1.0
Like the normal distribution, the exponential density function f(x)
A. is bell-shaped
B. approaches zero as x approaches infinity
C. approaches infinity as x approaches zero
D. is symmetrical
1.
options A,B,C are properties which are not necessarily found in all probability density functions
sum of all probabilities = 1
area under curve in probability density of continuous random variable is the sum of all probabilities
therefore area under the curve is 1.0
answer = D. The area under the curve is 1.0
2.
expnential density function curve
Normal distribution curve
we can see only thing that is common is : both approaches zero as x approaches infinity
answer : B. approaches zero as x approaches infinity
P.S. (please upvote if you find the answer satisfactory)
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