1. The distribution of SAT scores is normal with µ=500 and σ=100.
a. What SAT score, x-value separates the top 15% of the distribution from the rest?
b. What SAT score. X-value separates the top 20% of the distribution from the rest?
c. What SAT score. X-value separates the top 25% of the distribution from the rest?

2. Over the past 10 years the local school district has measured physical fitness for all high school freshmen. During that time, the average score on a treadmill endurance task has been µ=19.8 minutes with a standard deviation of σ=7.2 minutes. Assuming that the distribution is approximately normal, find each of the following probabilities.
a. What is the probability of randomly selecting a student with a treadmill time greater than 25 minutes? In symbols, p(X>25)= ?
b. What is the probability of randomly selecting a student with a time greater than 30 minutes? In symbols, p(x>30) ?
c. If the school required a minimum time of 10 minutes for students to pass the physical education course, what proportion of the freshman would fail?

3. Rochester, New York, averages µ=21.9 inches of snow for the month of December. The distribution of snowfall amounts is approximately normal with a standard deviation of σ=6.5 inches. This year a local jewelry store is advertising a refund of 50% off all purchases made in December, if we finish the month with more than 3 feet (36 inches) of total snowfall. What is the probability that the jewelry store will have to pay off on its promise?

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1. The distribution of SAT scores is normal with µ=500 and σ=100.
a) What SAT score, x-value separates the top 15% of the distribution from the rest?
b) What SAT score, x-value separates the top 20% of the distribution from the rest?
c) What SAT score, x-value separates the top 25% of the distribution from the rest?
Solution:
a)

Therefore, a SAT score of 604 separates the top 15% of the distribution from the rest.

b)

Therefore, a SAT score of 584 separates the ...

Solution Summary

The distribution of scores for SAT x-values are given.

1. The following are marks obtained by a group of 40 students on an English examination:
42 88 37 75 98 93 73 62
96 80 52 76 66 54 73 69
83 62 53 79 69 56 81 75
52 65 49 80 67 59 88 80
44 71 7

Help with this problem please:
Jane is told that her GMAT score is in the top 2% in her region at 28. The average score was 18. Tom scores 25 and Sandra scores 17. What are Jane, Tom, and Sandra's percentile scores?

1. For a sample selected from a population with a mean of µ=50 and a standard deviation of σ = 10:
a. What is the expected value of M and the standard error of M for a sample of n=4 scores?
b. What is the expected value of M and the standard error of M for a sample of n = 25 scores?
2. A population has a mean of µ

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1. What score would cut off the top 5 percent of scores?
2. What score would cut off the bottom 5 percent of scores?
3. What scor

A. Assuming that thedistribution of IQ is accurately represented by the bell curve in Figure 5.16, determine the proportion of people with IQs in each of the five cognitive classes defined by Herrnstein and Murray.
Figure 5.16
Thedistribution of IQ (See the attachment)
b. Although the cognitive classes above are defined

1. Briefly define each of the following:
a. Distribution of sample means
b. Expected value of M
c. Standard error of M
2. For a sample selected from a population with a mean of µ=50 and a standard deviation of s= 10:
a. What is expected value of M and the standard error of M for a sample of n = 4 scores?
b. What is the

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2. Under what circumstances should you use a grouped frequency distribution instead of a regular frequency distribution?

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- How does range affect standard deviation?
- What is a z-score, and how do z-scores relate to the mean of a set of data?
- Generally speaking, how is the percentage of data which lies in between two z-scores calculated?