Provide an appropriate response. 1) An observed frequency distribution of exam s

Question

Provide an appropriate response. 1) An observed frequency distribution of exam scores is as follows: Exam Score Under 60 60 - 69 70 - 79 80 - 89 90 - 100 Frequency 36 75 85 70 34 i) Assuming a normal distribution with = 75 and = 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 = 75 and = 15.

Explanation / Answer

i)

P( 59.5- 75 / 15 < z < 69.5 - 75 / 15 )

P( -1.03 < z < -0.37) = 0.3557 - 0.1515 = 0.2042

P( 69.5 - 75 / 15 < z < 79.5 - 75 / 15 )

P( -0.37 < z < 0.3 ) = 1 - 0.3557 - 0.3821 = 0.2622

P( 79.5 - 75 / 15 < z < 89.5 - 75 / 15 )

P( 0.3 <z < 0.97 ) = 0.3821 - 0.1660 = 0.2161

for the other question please post it ina new question

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