Use the following to answer questions: The table below presents the probability

Question

Use the following to answer questions: The table below presents the probability distribution for X = the number of email messages you will receive in the next 10 minutes

X

0

1

2

3

P(X)

.35

.35

.25

.05

What is the probability that no emails will be received?

What is the probability that at least one email will be received?

What is E(X), the expected number of emails that will be received?

What is Var(X), the variance of the number of emails that will be received?

What is the Std(X), the standard deviation of the number of emails that will be received?

X

0

1

2

3

P(X)

.35

.35

.25

.05

Explanation / Answer

P(0)=0.35

P(x>=1)=P(1,2,3)=0.35+0.25+0.05=0.62

E(x)=Sumxp(x)=0+0.35+2*0.25+3*0.05=1

V(x)=sumx^2p(x)-(E(x))^2=1.8-1=0.8

Std(x)=sqrtV(x)=0.894

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