Quizzes and Exercises of Data Description

These quizzes and exercises help us review and practice what we obtained in this chapter. They are presented in "show-hide" form similar to the sections of a web page as we are already familiar. Quizzes are multiple choice questions. After choosing an option, an announcement of result appears. To return back to this page, we click "OK" on the announcement. Of course you can choose another option.

In exercises, we are required to calculate a value then fill it in an empty rectangle. Note that in this rectangle, only value is acceptable, its unit is not required. After filling the result, we click on "Answer". If the answer is correct, the border of the rectangle is green and there is green "V" symbol in the adjacent square. If the answer is wrong, the border of the rectangle is red and there is red "X" symbol in the adjacent square. We can erase the answer and try again by clicking on "Retry".

For each exercise, there is a hidden solution. To show this solution, we click on "Solution" tab. But try to solve exercises by ourself, don't abuse these solutions.

Quiz 1

In order to investigate the effect of 2 nominal variables simultaneously, we use:

Quiz 2

An exercise consists of 10 quizzes for a class of 130 students. The result of this exercise is shown in Table 1.

Table 1 Result of exercise
Number of correct answer	Frequency	Cumulative frequency
0	2	2
1	5	7
2	9	16
3	10	26
4	13	36
5	22	60
6	22	82
7	21	106
8	13	121
9	10	127
10	3	130

Question 2a

Which is not correct in Table 1 ?

Question 2b

When number of correct answer is 7, what is cumulative frequency ?

Question 2c

When number of correct answer is 4, what is relative cumulative frequency ?

Quiz 3

To investigate the relationships between blood pressure and age of patients, the chart the most suitable is

Quiz 4

Standard deviation

Quiz 5

In an examination of a class of 80 students, the minimal score is 2, the maximal score is 10.

Quiz 6

Exercise 1

The blood pressure of 8 patients are :

77 105 117 84 96 72 105 124

a. What is the mean of blood pressure of these patients ?

b. What is the median of blood pressure of these patients ?

c. What is the mode of blood pressure of these patients ?

d. Consider these patients as a sample taken from a hospital. What is the standard deviation of blood pressure of these patients ?

Solution

a. Mean : 97,5

b. Median : 100,5

c. Mode : 105

d. Standard deviation : 18,7

Exercise 2

In a survey about self study of student, the time for self study of 20 students is given in Table 2.

Table 2 Time for self study of students (unit : hours/week)
12	20	13	16	21
33	17	15	7	2
17	13	16	19	8
15	19	15	10	10

a. What is the mean of time for self study of these students (unit: hours/week)?

b. What is the median of time for self study of these students (unit: hours/week)?

c. These students are taken randomly from a university, what is the standard deviation of time for self study of these students (unit : hours/week)?

d. What is the first quartile of this data (unit: hours/week)?

e. What is the third quartile of this data (unit : hours/week)?

f. If the whisker coefficient is 1,5, what is the length of whisker (unit: hours/week)?

Quiz g

If the whisker coefficient is 1,5, how many outliers are there in Table 2 ?

Solution

To facilitate the determination of questioned values, we rearrange 20 numbers in Table 2 in ascending order. The new arrangement is shown in Table 3.

Table 3 Time of self study of students in ascending order (unit: hours/week)
2	7	8	10	10
12	13	13	15	15
15	16	16	17	17
19	19	20	21	33

a. Mean of time of self study : 14,9 hours/week

b. Median of time of self study is the average of `10^(th)` and `11^(th)` numbers in Table 3:
15 hours/week

c. Standard deviation of this data : 6,4 hours/week

d. The first quartile of this data is the average of `5^(th)` and `6^(th)` numbers in Table 3:
`Q_1=11` hours/week

e. The third quartile of this data is the average of `15^(th)` and `16^(th)` numbers in Table 3:
`Q_3=18` hours/week

f. Interquartile range : `IQR=Q_3-Q_1=18-11=7` hours/week
If whisker coefficient is 1,5 then whisker length is:
`R=1,5 IQR=1,5xx7=10,5` hours/week.

g. To be outlier, the self study time must be smaller than:
`Q_1-R=11-10,5=0,5` hours/week
or must be greater than :
`Q_3+R=18+10,5=28,5` hours/week.

So, in Table 3 there is an outlier, it is `20^(th)` number with value of 33.

This web page was last updated on 01 December 2018.