Statistics in a Modern World 800 Homework 3 NAME:_________________________________

Homework 3 Exercises Assigned from Chapters 7-8 (21 pts.) due Fri., October 2 in Lecture.

CHAPTER 7

#1 (4 pts.) At the beginning of this chapter, the following exam scores were listed: 75, 95, 60, 93, 85, 84, 76, 92, 62, 83, 80, 90, 64, 75, 79, 32, 78, 64, 98, 73, 88, 61, 82, 68, 79, 78, 80, 55.

1. On a separate sheet of paper (staple it to the back), create a stemplot for the test scores.
2. The shape as shown by the stemplot is (i) symmetric (ii) skewed right (iii) skewed left
3. The shape is (i) unimodal (ii) bimodal
4. Are there any outliers? If so, tell what they are.

#2. (2 pts.) Refer to the test scores in Exercise 1.

1. List the values of the Five Number Summary, from lowest to highest.
2. On your separate sheet of paper, create a boxplot.

#3 (1 pt.) On your separate sheet of paper, create a histogram for the test scores.

#8 (2 pts.) Find the mean and standard deviation of these numbers: 10, 20, 25, 30, 40.

#12 (2 pts.) In each of the following cases, which would probably be higher, the mean or the median, or would they be about equal?

1. Salaries in a company employing 100 factory workers and 2 highly paid executives (i) mean higher (ii) median higher (iii) about equal
2. Ages at which residents of a suburban city die, including everything from infant deaths to the most elderly (i) mean higher (ii) median higher (iii) about equal
3. Heights of all 7-year-old children in a large city (i) mean higher (ii) median higher (iii) about equal
4. Shoe sizes of adult women (i) mean higher (ii) median higher (iii) about equal

CHAPTER 8

# 1 (1.5 pts.) Using Table 8.1 p.157, determine the percentage of the population falling BELOW each of the following standard scores:

1. -1.00
2. 1.96
3. 0.84

#2 (1.5 pts.) Using Table 8.1, determine the percentage of the population falling ABOVE each of the following standard scores:

1. 1.28
2. -0.25
3. 2.33

#3 (2 pts.) Using Table 8.1, determine the standard score that has the following percentage of the population BELOW it:

1. 25%
2. 75%
3. 45%
4. 98%

#4 (2 pts.) Using Table 8.1, determine the standard score that has the following percentage of the population ABOVE it:

1. 2%
2. 50%
3. 75%
4. 10%

#5 (1 pt.) Using Table 8.1, determine the percentage of the population falling between the two standard scores given:

1. -1.28 and 1.75
2. 0.0 and 1.0

#9 (1 pt.) Stanford-Binet IQ's have mean 100, standard deviation 16. Mensa is an organization that allows people to join only if their IQ's are in the top 2% of the population. What is the lowest Stanford-Binet IQ you could have and still be eligible to join Mensa? Show your work.

#14 (1 pt.) A graduate school program in English will admit only students with GRE verbal ability scores in the top 30%. What is the lowest GRE score they will accept? (Recall the mean is 497 and the standard deviation is 115.) Show your work.