SOLUTION: A statistics teacher knows that the grades obtained in his course are normally distributed with a mean of 70 and a standard deviation of 15. For a random sample of 17 students find
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Question 928624: A statistics teacher knows that the grades obtained in his course are normally distributed with a mean of 70 and a standard deviation of 15. For a random sample of 17 students find the probability that their grade will be
A) Over 75
B) under 50
C) between 60 and 70 Answer by ewatrrr(24785) (Show Source):
You can put this solution on YOUR website! mean of 70 and a standard deviation of 15.
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Using a TI calculator 0r similarly a Casio fx-115 ES plus
P(x > 75) = P( z > 5/3.638) = normalcdf(1.3744, 100)= .0847 0r 8.47%
P(x < 50) = P(z < -20/3.638) = normalcdf(-100, -5.498)= .0000000192
P( 60< x < 70) = P(-10/3.638 < z < 10/3.638) = normalcdf(-2.7488, 2.7488)= .9940
