Chapter Chapters : Chapter 5 And Chapter 6

850 Words Jun 11th, 2015 4 Pages
Brianna Delgado
June 11, 2015
STAT: 1020
Assignment #3: Chapter 5 and Chapter 6
CHAPTER 5
3. From the mid-1960s to the early 1990s, there was a slow but steady decline in SAT scores. For example, take the verbal SAT. The average in 1967 was about 543; by 1994, the average was down to about 499. However, the AD stayed close to 110. The drop in averages has a large effect on the tails of the distribution. (a) Estimate the percentage of students scoring over 700 in 1967. (b) Estimate the percentage of students scoring over 700 in 1994.
You may assume that the histograms follow the normal curve.
Answer:
(a) 5.5%
(b) 2.3%
5. In HANESS, the men age 18 and over had an average height of 69 inches and an SD of 3 inches. The histograms is show below, with a normal curve. The percentage of men with heights between 66 inches and 72 inches is exactly equal to the area between (a) and (b) under (c). This percentage is approximately equal to the area between (d) and (e) under the (f). Fill in the blanks.
For (a), (b), (d), and (e), your options are: 66 inches, 72 inches, -1, +1.
For (c) and (f), your options are: normal curve and histogram.
Answer:
a) -1
b) +1
c) Normal curve
d) 66 inches
e) 72 inches
f) histogra
7. Among freshmen at a certain university, scores on the Math SAT followed the normal curve, with an average of 550 and an SD of 100.
(a) Approximately, what is the percentile rank for a student who scored 400 on the Math SAT? And Why?
(b) Approximately, what is the 75th…

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