Probability and statistics

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5. The probabilities that the lifetime of a randomly chosen device is below average, average, above average are respectively 0.2, 0.5, and 0.3. The probability that the 3 randomly chosen devices lifetimes of 2 are above average and 1 below average equals

a. 0.054
b. 0.018
c. 0.036
d. 0.012

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• Probability and statistics - ,

.054

• Probability and statistics - ,

Question 1 of 1:
Finding Standard Deviation
A simple random sample of FICO credit rating scores is listed below:

714 751 664 789 818 779 698 836 753 834 693 802
Find range, variance, and standard deviation.
As of this writing, the mean FICO score was reported to be 678. Based on these results, is a FICO score of 500 unusual? Why or why not?