The average of the weights of all the boys in Sixth Grade in a school is 100 pounds and its standard deviation is 14.142, while the average of the weights of all the girls in sixth grade in that school is 85 pounds and its standard deviation is 12.247 pounds. It is known that, both for boys and for girls, weights follow a normal distribution. Then the probability that the average of the weights of 20 boys and that of 25 girls will differ by at most 20 pounds is:
The average of the weights of all the boys in Sixth Grade in a school is 100 pounds and its standard deviation is 14.142, while the average of the weights of all the girls in sixth grade in that school is 85 pounds and its standard deviation is 12.247 pounds. It is known that, both for boys and for girls, weights follow a normal distribution. Then the probability that the average of the weights of 20 boys and that of 25 girls will differ by at most 20 pounds is:
Chapter8: Sequences, Series,and Probability
Section8.7: Probability
Problem 11ECP: A manufacturer has determined that a machine averages one faulty unit for every 500 it produces....
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Transcribed Image Text:The average of the weights of all the boys in Sixth Grade in a school is 100 pounds and its
standard deviation is 14.142, while the average of the weights of all the girls in sixth grade in
that school is 85 pounds and its standard deviation is 12.247 pounds. It is known that, both for
boys and for girls, weights follow a normal distribution. Then the probability that the average of
the weights of 20 boys and that of 25 girls will differ by at most 20 pounds is:
a) 0.1056
b) 0.8944
c) 0.3944
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