Compute the mean and standard deviation of the random variable with the given discrete probability distribution.

x	Px
7	0.13
3	0.17
2	0.23
4	0.47

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Part 1 of 2

(a) Find the mean. Round the answer to three decimal places, if necessary.

The mean is .

Part:1 / 2

1 of 2 Parts Complete

Part 2 of 2

(b) Find the standard deviation. Round the answer to at least three decimal places.

The standard deviation is .

Fifteen items or less:The number of customers in line at a supermarket express checkout counter is a random variable with the following probability distribution.

x	0	1	2	3	4	5
Px	0.05	0.25	0.30	0.20	0.10	0.10

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Part 1 of 4

(a) Find

P4

.

=P4

Part 2 of 4

(b) Find

P

No more than

1

.

P No more than =1

Part 3 of 4

(c) Find the probability that no one is in line.

The probability that no one is in line is .

Part:3 / 4

3 of 4 Parts Complete

Part 4 of 4

(d) Find the probability that at least three people are in line.

The probability that at least three people are in line is .

Fifteen items or less:The number of customers in line at a supermarket express checkout counter is a random variable with the following probability distribution.

x	0	1	2	3	4	5
Px	0.05	0.25	0.30	0.25	0.10	0.05

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Part 1 of 3

(a) Compute the mean

X

. Round the answer to two decimal places.

=X

Part 2 of 3

(b) Compute the standard deviation

X

. Round your answer to

4

decimal places if necessary.

=X

Part:2 / 3

2 of 3 Parts Complete

Part 3 of 3

(c) If each customer takes

2

minutes to check out, what is the probability that it will take more than

4

minutes for all the customers currently in line to check out?

The probability that it will take more than

4

minutes for all the customers currently in line to check out is