Reference no: EM132124110
Normal Curve (using the Z/Normal Chart)
Please make a separate sketch for each question!!. Put all of the information and answers on your pictures (percents inside the curve, z-scores under the curve, mean and raw scores under the curve...).
A. (determining exact percentages, not approximations, from z scores using the Z/Normal Chart) An education researcher has been studying test anxiety using a particular measure, which she administers to students prior to midterm exams. On the measure, she has found that the distribution of scores follows a 'normal' curve pattern. Using a Normal/Z chart, determine what percentage of students have scores:
1) below z = 1.5
2) below z = -1.5
3) above z = 2.1
4) above z = -.45
5) between z = -1.68 and z = -2.78
_93.32%_ _6.68%__ _1.79%__ _67.36%_
_4.38%__
B. (determining exact z scores from percentages, using the Z/Normal Chart)
Assuming a normally distributed set of scores for a Spanish test, what z score corresponds to (is the cutoff for) the following parts of the distribution:
6) top 15%
7) bottom 30%
8) top 5%
9) 90th percentile __+1.28__
10) the middle 60% (two answers) __-.84___ and _+.84__
C. (going from percentage to z-score to raw score)
Consider a medical test for which M = 200 and SD = 40. If the results are normally distributed, what (raw) score would a patient need to have, to be in the:
_+1.04_ _-.52__
_+1.65_
11) bottom 40% __190_
12) 80th percentile __233.6_
13) top 1% __293.2_
14) 33rd percentile __182.4__
15) extreme 5% (two answers: cutoff for top 2.5% and bottom 2.5%)
_121.6_ and _278.4_
D. (going from raw score to z-score to percentage)
Assuming that you had a test for which the results fit a normal curve, the mean is 70 and thestandard deviation is 8, what percent of students have scores:
16) below a 74? 69.15%
17) below a 60? 10.56%
18) above an 82? 6.68%
19) between 74 and 82? _24.17%_
20) between 66 and 74? _38.30%_