Homework 1
Stat 4220
1) A random sample of five men shows their height in inches:
65.51, 72.30, 68.31, 67.05, 70.68
Calculate the standard deviation by hand using the method shown in class (or in the book)
Xi
xi-𝑥̅
(xi-𝑥̅ )2
 x
 x 
2
i
 x
 x
2
i

n 1
 x
 x
2
i
n 1
=
2) In a statistics class of 30 students, the mean score on the midterm was 72. In another class of 40
students the mean score was 79. What was the mean for the two classes combined?
3) Clock times for n=20 computers follow:
196
212
200
242
206
178
198
182
222
198
188
166
184
204
198
178
160
164
182
230
Draw a histogram of these data. Make the bars cover intervals of clock times that are 10 wide
beginning at 155 (155 to 164, 165 to 174, and so on).
4) The following data shows the number of people who walk over a particular bridge on random
days. Draw the boxplot for the data.
247 275 262 293 266 256 256 253 247 298 320
350 278 279 304 247 236 304 230 251 291 261
5) Here are histograms, boxplots and summary statistics for four different data sets:
Match the Histogram, Boxplot and Data Set together
Data Set
1
2
3
4
Histogram
Boxplot