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Probability, Mean and Standard Deviation of Distribution

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Problem D:
The table below shows the probability distribution for the daily demand of microcomputers at a local store.
DEMAND PROBABILITY
0 0.2
1 0.2
2 0.3
3 0.2
4 0.1
BASED ON THIS TABLE - ANSWER QUESTIONS 13 AND 14 BELOW.

13. The expected daily demand is:
a. 1.2 b. 2.2 c. 1.0 d. 1.8

20. A professor teaches two sections (sections A and B) of an introductory business statistics class. Both sections have a mean score of 75. Section A only has 5 students and they have all received a score of 75, while section B has 15 students with a mean score of 75 and a variance of 12. What is the standard deviation of the combined class (N = 20, treat as the population).
A) 9 B) 6 C) 4 D) 3 E) 2

21. The average size of insurance claims processed by Good-Wish Insurance Company for the month of August is $615 with a standard deviation of $135. If you assume that the population of insurance claims is not symmetric, what is the probability that the claim is between $345 and $885?
A) 95% B) 88.89% C) 55.56% D) 84% E) 75%

PROBLEM E: Use the following to answer questions 22-24:

The College of Business Administration at Acorn University offers a major in Finance. Based on historical records, 30% of the College of Business students major in Finance. A random sample of 20 students is selected.

22. What is the probability that no more than 3 of the selected students are majoring in Finance?
A) .0716 B) .027 C) .09 D) .107 E) .0354

23. What is the probability that at least 16 of the students are not majoring in Finance?
A) .1304 B) .0716 C) .2374 D) .7626 E) .8696

24. What are the mean and the standard deviation of this distribution?
A) .3 and 2.44
B) 3 and 4.2
C) 6 and 4.2
D) 6 and 2.05
E) 20 and 2.05

25. If z is a standard normal random variable, compute the probability of P(-1.95 < z < 0.39)
a. 0.3227 b. -0.3227 c. -0.6261 d. 0.6261

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