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In: Statistics and Probability

The distribution of scores on a recent test closely followed a Normal Distribution with a mean...

The distribution of scores on a recent test closely followed a Normal Distribution with a mean of 22 points and a standard deviation of 2 points. For this question, DO NOT apply the standard deviation rule.

(a) What proportion of the students scored at least 21 points on this test, rounded to five decimal places?

(b) What is the 63 percentile of the distribution of test scores, rounded to three decimal places?

Solutions

Expert Solution

Given that,

a)

= 1 - p ( z < -0.5 ) By using standard normal table

= 1 - 0.30854 = 0.69146

b)

By using excel function "=NORM.INV(0.63,0,1)" the indicated z score for area 0.63 is 0.332.

= 22 + (0.332*2) = 22.664

orchestra answered 1 year ago
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