SOLUTION: The test score of a math class with 800 students are distributed normally with a mean of 75 and a standard deviation of 7. a) What percentage of a class has a test score between

Question 1198593: The test score of a math class with 800 students are distributed normally with a mean of 75 and a standard deviation of 7.
a) What percentage of a class has a test score between 68 and 82?
b) Approximately how many students have a test score between 61 and 89?
c) What is the probability that a student chosen at random has a test score between 54 and 75?
d) Approximately how many students have a test score greater than or equal to 96?
Answer by ikleyn(52810) (Show Source): You can put this solution on YOUR website!
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The test score of a math class with 800 students are distributed normally with a mean of 75 and a standard deviation of 7.
a) What percentage of a class has a test score between 68 and 82?
b) Approximately how many students have a test score between 61 and 89?
c) What is the probability that a student chosen at random has a test score between 54 and 75?
d) Approximately how many students have a test score greater than or equal to 96?
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(a)  They want you find the area under the specified normal curve between given raw scores

     For it, use you calculator P = normalcfd(68, 82, 75, 7)

     or use online free of charge calculator https://onlinestatbook.com/2/calculators/normal_dist.html

     The answer is 0.6827  (rounded).



(b)  First find the probability as the area under the specified normal curve between the given raw scores 

     For it, use you calculator  P = normalcfd(61, 89, 75, 7)

     or use online free of charge calculator https://onlinestatbook.com/2/calculators/normal_dist.html

     The probability (the area under the curve)  is 0.9545  (rounded).


     Therefore, the answer to question (b) is this product  0.9545*800.    

     Use your calculator and round appropriately.

Solved.

In the future, do not pack too many questions in one post.

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