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5.6. ComputeE[X]if Xhas a density function given by

(a)f(x)=14xe-x2x>00otherwise;

(b)f(x)=c(1−x2)-1<x<10otherwise;

(c)f(x)=5x2x>50x≤5.

Short Answer

Expert verified

Thus the answer of given question is

(a),E(X)=4

(b),E(X)=0

(c),E(X)=∞

Step by step solution

01

Given Information.

f(x)=14xe-x2x>00otherwise

02

Explanation.

E(x)=∫-∞∞x.14xe-x2dx

=14∫0∞x9e-x2dx

x2=4,x=2y

E(X)=∫0∞2.y2e-ydy=2∫0∞y3-1e-1dy

=2×2=4

03

Explanation.

f(x)=c(1-x2)−1<x<10otherwise

∫-∞∞(1-x2)dx=1,∫-∞∞c(1-x2)dx=1

c.43=1⇒c=34

E(X)=∫-∞∞x.34(1-x2)dx=34∫-11(x-34)dx

=34x22-x441-1

=34×0=0

04

Explanation.

E(X)=∫-∞∞5x0dx=∫50xdx=5

=5ux15∞

=∞

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Most popular questions from this chapter

If Xis a normal random variable with parameters μ=10and σ2=36, compute

(a)role="math" localid="1646719347104" PX>5

(b)role="math" localid="1646719357568" P4<X<16

(c)role="math" localid="1646719367217" PX<8

(d)PX<20

(e)PX>16

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