Use the z-cores and the corresponding percentiles shown at the top of the next c

Question

Use the z-cores and the corresponding percentiles shown at the top of the next column to solve this exercise. Test scores are normally distributed with a mean of 74 and a standard deviation of 10. What percentage of the scores are above 88? 9. z-scores Percentile 1.1 1.2 1.3 1.4 1.5 86.43 88.49 90.32 91.92 93.32 10. Using a random sample of 100 students from a campus of approximately 12000 students, 60% of the students in the sample said they were very satisfied with their professors. Find the margin oferror in this percent +100%

Explanation / Answer

Q9.

the PDF of normal distribution is = 1/ * 2 * e ^ -(x-u)^2/ 2^2
standard normal distribution is a normal distribution with a,
mean of 0,
standard deviation of 1
equation of the normal curve is ( Z )= x - u / sd ~ N(0,1)
mean ( u ) = 74
standard Deviation ( sd )= 10
P(X > 88) = (88-74)/10
= 14/10 = 1.4
= P ( Z >1.4) From Standard Normal Table
= 0.0808

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