Question 477951: An educational testing cooperation has designed a standard test of
mechanical aptitude. Score on this test are normally distributed with a
mean of 65 and a standard deviation of 3.
a. If a subject is randomly selected and tested, find the probability that his
score will be between 61 and 69.
b. If a subject is randomly selected and tested, find the probability that his
score will be below 57.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Score on this test are normally distributed with a
mean of 65 and a standard deviation of 3.
a. If a subject is randomly selected and tested, find the probability that his
score will be between 61 and 69.
z(61) = (61-65)/3 = -4/3
z(69) = (69-65)/3 = 4/3
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P(61<= x <= 69) = P(-4/3 <= z <= 4/3) = 0.8176
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b. If a subject is randomly selected and tested, find the probability that his
score will be below 57.
z(57) = (57-65)/3 = -8/3
P(x < 57) = P(z < -8/3) = 0.0038
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Cheers,
Stan H.
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