6. Show that if f is a PDF and the integral [x²f(x) dx exists, then the integral |zx|f(x) dx exists. (This is from question number 14 on page 280 of the book which includes a helpful hint.) Why is this result important? (Why would we care about the existence of the second integral?)

Calculus For The Life Sciences
2nd Edition
ISBN:9780321964038
Author:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Chapter13: Probability And Calculus
Section13.CR: Chapter 13 Review
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Question
6.
Show that if f is a PDF and the integral
[2²f(z) dz
just do #6
exists, then the integral
|x|f(x) dx
exists. (This is from question number 14 on page 280 of the book which includes a helpful
hint.) Why is this result important? (Why would we care about the existence of the second
integral?)
280 #14
Let X be a continuous random variable with density function fx(x). Show
that if
x² fx (x) dx <∞,
then
+∞
|x|fx (x) dx <∞ .
Hint: Except on the interval [-1,1], the first integrand is greater than the
second integrand.
-∞
Transcribed Image Text:6. Show that if f is a PDF and the integral [2²f(z) dz just do #6 exists, then the integral |x|f(x) dx exists. (This is from question number 14 on page 280 of the book which includes a helpful hint.) Why is this result important? (Why would we care about the existence of the second integral?) 280 #14 Let X be a continuous random variable with density function fx(x). Show that if x² fx (x) dx <∞, then +∞ |x|fx (x) dx <∞ . Hint: Except on the interval [-1,1], the first integrand is greater than the second integrand. -∞
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