EBook Problems Distrib MeanVar

EBook Problems Set - Expectation (Mean) and Variance

Problem 1

Ming’s Seafood Shop stocks live lobsters. Ming pays $6.00 for each lobster and sells each one for $12.00. The demand X for these lobsters in a given day has the following probability mass function.

X	0	1	2	3	4	5
P(x)	0.05	0.15	0.30	0.20	0.20	0.1

What is the Expected Demand?

• Choose one answer.

(a) 13.5

(b) 3.1

(c) 2.65

(d) 5.2

Answer

 (c)

Problem 2

If sampling distributions of sample means are examined for samples of size 1, 5, 10, 16 and 50, you will notice that as sample size increases, the shape of the sampling distribution appears more like that of the:

• Choose one answer.

(a) normal distribution

(b) uniform distribution

(c) population distribution

(d) binomial distribution

Answer

 (a)

Problem 3

The number of flaws on an electroplated automobile grill is known to have following probability distribution:

X	0	1	2	3
P(X)	0.8	0.1	0.05	0.05

For a random sample of 200 grills, calculate the approximate probability that the average number of flaws per grill exceeds 0.4

• Choose one answer.

(a) 0.0002

(b) None of the above

(c) 1

(d) 0.1860 approximately

Answer

 (d)

Problem 4

The number of flaws on an electroplated automobile grill is known to have following probability distribution:

X	0	1	2	3
P(X)	0.8	0.1	0.05	0.05

What would be the standard deviation of the sample means if we took 100 samples, each sample with 200 grills, and computed their sample means?

• Choose one answer.

(a) None of the above

(b) 0.89269

(c) 0.0560

(d) 0.6275

Answer

 (c)

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