SOLUTION: 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 o
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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
------------------------
P(61<= x <= 69) = P(-4/3 <= z <= 4/3) = 0.8176
------------------------------------------------------
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
===================================
Cheers,
Stan H.
 
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