Solve by Minitab only and please provide all steps An observed frequency distrib

Question

Solve by Minitab only and please provide all steps

An observed frequency distribution of exam scores is as follows: i) Assuming a normal distribution with mu = 75 and sigma = 15, find the probability of a randomly selected subject belonging to each class. (Use boundaries of 59.5, 69.5, 79.5, 89.5, 100.) ii) Using the probabilities found in part (i), find the expected frequency for each category. iii) Use a 0.05 significance level to test the claim that the exam scores were randomly selected from a normally distributed population with mu = 75 and sigma = 15.

Explanation / Answer

for as we know that z score =(X-mean)/std deviation

with help of z value from above distribtion with probabilty from normal distribution:

for chi stat 10.8502 and 4 degree of freedom; p value =0.0283

as p vlaue is less then 0.05 level; we reject that above came from normally distributed population,

observed Expected Chi square score Probability O E=total*p =(O-E)^2/E <60 0.151 36.00 45.22 1.88 60-69 0.206 75.00 61.86 2.79 70-79 0.261 85.00 78.29 0.57 80-89 0.215 70.00 64.57 0.46 >90 0.167 34.00 50.06 5.15 300 300 10.8502

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