1. Exercises on Measures of Central Tendency Enter

2. There are seven multiple-choice questions in this exercise. Click the letter to select the corresponding answer. Enter

3. 1.This is the frequency distribution of the ages of students in a class. AgeFrequency 117 1219 1310 144 Find out their mean age. A B C 12 12.3 12.5 D 19

4. Bingo ！ Mean age Next question AgeFrequency 117 1219 1310 144

5. 12 is the mode, not the mean. Try again ！ Hints: Return AgeFrequency 117 1219 1310 144 Mean age

6. Sorry! You forgot to count the frequencies! Try again! Hints: Return AgeFrequency 117 1219 1310 144 Mean AgeFrequency 111 121 131 141 Mean age = ?

7. 19 is the frequency of 12 year-old. That means there are 19 students who are 12 years old. You should be looking for the mean of the students’ age. Try again! Hints: Return AgeFrequency 117 1219 1310 144 Mean age

8. 2.This is the frequency distribution of the weights of 50 members of a children’s choir. Weight （ kg ） Class mark, x kgFrequency 36-40382 41-45438 46-504811 51-555312 56-605813 61-65634 A B C 51.8 kg 56-60 kg 50.5 kg Find out their mean weight.

9. Bingo ！ Mean weight Next question ( kg )

10. 56-60 kg is the modal class, not the mean weight. Try again! Hints ： Mean weight Return Weight （ kg ） Class mark, x kgFrequency 36-40382 41-45438 46-504811 51-555312 56-605813 61-65634

11. Sorry! You forgot to count the frequencies. Try again! Hints ： Return Mean weight WeightFrequency Weight （ kg ） Class mark, x kgFrequency 36-40382 41-45438 46-504811 51-555312 56-605813 61-65634 Mean weight= ?

12. 3.The table shows the number of mobile phones owned by 100 families. Number of mobile phonesFrequency 22 36 438 516 620 718 Find the mode. A B C 4 4.5 5 D 38

13. Mode = 4 Bingo ！ Mode is the most frequent datum/data in a set of data. Therefore: Next question

14. 5 is the mean of mobile phones owned by each family, not the mode. Hints ： Mode is the most frequent datum/data in a set of data. Return Try again!

15. Hints ： Mode is the most frequent datum/data in a set of data. Return 38 is the frequency of 4. That means there are 38 families that have 4 mobile phones. You should be looking for the mode ！ Try again!

16. Sorry, your answer is wrong. Try again! Hints ： Mode is the most frequent data in a set of data. Return

17. 4.This is the frequency distribution of the time spent by Kelly on waiting for the bus last week. Time (minutes)Class mark (minutes)Frequency (days) 1-530 6-10815 11-151312 16-201812 21-25231 Find the modal class. A C D 12.9 minutes 11-15 and 16-20 minutes 6-10 minutes B8 minutes

18. Bingo ！ Modal class is the most frequent class in a set of data. Therefore: Modal class = 6-10 minutes Next question

19. 12.9 is the mean of the time spent on waiting for the bus, not the modal class. Hints ： Modal class is the most frequent class in a set of data. Return Try again!

20. 8 is the class mark of the class “6-10 minutes”. You should be looking for the modal class of the time spent by Kelly on waiting for the bus in the past 40 days. Hints ： Modal class is the most frequent class in a set of data. Return Try again!

21. Sorry, your answer is wrong. Try again! Hints ： Modal class is the most frequent class in a set of data. Return

22. 5.This is the frequency distribution of the time spent by 80 students in finishing a 3,000-meter track. Time （ minutes ） Class mark (minutes ） Frequency (No. of person) 10-15134 16-20189 21-252314 26-302814 31-35339 Find the modal class. A B C 16-20 and 31-35 minutes 21-25 and 26-30 minutes 15.3 minutes

23. Bingo ！ Modal class is the most frequent class in a set of data. Therefore: Modal class = 21-25 and 26-30 minutes Next question

24. 15.3 minutes is the mean of the time needed to finish a 3,000-meter track, not the modal class! Hints ： Modal class is the most frequent class in a set of data. Return Try again!

25. Sorry, your answer is wrong. Try again! Hints ： Modal class is the most frequent class in a set of data. Return

26. 6.This is the cumulative frequency polygon of the salaries of a company’s employees. Find the median. A B C 15000 dollars 15400 dollars 15800 dollars

27. Bingo ！ Since there are 90 employees in the company, there median can be found at the 45th employee. Therefore: Median=15000 dollars Next question

28. Sorry, you didn’t pay attention to the cumulative number of employee. Since there are 90 employees in the company, there median can be found at the 45th employee. Try again! Hints ： Return

29. 7.This is the cumulative frequency polygon of rainfall in Island West during the past 40 days. Find the median. B C D 70 mm 77 mm 85 mm A 20 mm

30. Bingo ！ The median of rainfall in 40 days can be found at the 20 th day. Therefore: Median = 70 mm End

31. Sorry, you didn’t pay attention to the cumulative number of days. Try again! Hints ： The median of rainfall in 40 days can be found at the 20 th day. Return

32. The End