12. The random variable X represents the annual salaries in dollarsof a group of
ID: 2915362 • Letter: 1
Question
12. The random variable X represents the annual salaries in dollarsof a group of teachers. Find the expected value E(X).X = {$30,000, $40,000, $50,000}
P(30,000) = 0.1; P(40,000) = 0.5; P(50,000) = 0.4
$35,000
$25,000
$43,000
$49,000
13. Scores on an exam for entering a private school are normallydistributed, with a mean of 79 and a standard deviation of 5. To beeligible to enter, a person must score in the top 10%. What is thelowest score you can earn and still be eligible to enter?
86
84
79
75
14. A shipment of 50 television sets contains 4 defective units.How many ways can a vending company buy four of these units andreceive no defective units?
163,185
123,965
145,290
178,431
15. The time required to process a ton of sugar cane in a plant inCentral America in a recent year was normally distributed with amean 5 days and a standard deviation of 0.5 days (i.e., 12 hours).What is the probability that it will take more than 6 days toprocess a ton of sugar cane?
0.9772
0.0228
0.8413
0.1587
Explanation / Answer
12. The random variable X represents the annual salaries in dollarsof a group of teachers. Find the expected value E(X). X = {$30,000, $40,000, $50,000} P(30,000) = 0.1; P(40,000) = 0.5; P(50,000) = 0.4 $35,000 $25,000 $43,000 $49,000 13. Scores on an exam for entering a private school are normallydistributed, with a mean of 79 and a standard deviation of 5. To beeligible to enter, a person must score in the top 10%. What is thelowest score you can earn and still be eligible to enter? 8684 79 75 14. A shipment of 50 television sets contains 4 defective units.How many ways can a vending company buy four of these units andreceive no defective units? 163,185123,965 145,290 178,431 15. The time required to process a ton of sugar cane in a plant inCentral America in a recent year was normally distributed with amean 5 days and a standard deviation of 0.5 days (i.e., 12 hours).What is the probability that it will take more than 6 days toprocess a ton of sugar cane? 0.9772 0.0228 0.8413 0.1587
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