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# Practice

Mean, Mode and Median
1. The mean of 2, b, 5, c, 12 is 6.4. The mean of 4, 4, 2b, 7, c, 11 is 7. Find the values of b
and c.
2. (i) A class has 30 boys and 20 girls. The mean mark of a test for the boys is 50 and the
mean mark for the girls is 20. Find the mean mark for the whole class.
(ii) In a class, the mean mark of a test is 60 for the boys and 70 for the girls. The total
mark received is 600 for the boys and 1400 for the girls. Find the mean mark for the
whole class.
(iii)

A class has 10 boys and 15 girls. In a test, the total mark for the boys is 900
and the total mark for the girls is 1000. Find the mean mark for the whole class.

3. The following table shows the distribution of heights for 25 boys.
Height (cm)
Number of students
(i)
(ii)
(iii)

150
4

156
4

158
8

159
4

161
5

What are the mode and the modal frequency?
What is the median?
Calculate the mean.

4. 500 batteries were tested for their lifespans to the nearest hour. The results are as follows:
Lifespan (x hours)
Frequency

53 ≤ x < 56
100

56 ≤ x < 59
150

59 ≤ x < 62
200

62 ≤ x < 65
50

Estimate the (i) mode, (ii) median, (iii) mean of the lifespans of the batteries in hours.
5. The table shows the numbers of books read by 100 students in one year.
Frequency

1 – 12
10

13 – 24
20

25 – 36
15

37 – 48
30

49 – 60
15

61 – 72
10

Estimate the (i) mode, (ii) median, (iii) mean of the number of books read.
6. The following table shows the distribution of pocket money for 30 students per month.
Pocket money per month (\$)
Number of students

15
8

Calculate the mean.

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32
5

45
10

100
4

200
3

what is the range of values of x? (iii) If the modal score of the distribution is 20. It should be 75. 509. (a) What is the range of value of x if 40 is the mode? (b) What is the range of value of x if 50 is the mode? 10. Score Frequency 10 60 20 70 30 20 40 x 50 30 (i) What is the value of x if the distribution has two modes? (ii) If the modal score of the distribution is 40. calculate the values of x and y. Score Frequency 40 9 60 x 80 6 In this distribution of scores. 19 9. 14. Score Frequency 10 60 20 70 y 20 40 x 50 30 If the mean of the distribution is 24 and x + y = 45. 38. 27. Score Frequency 10 60 20 70 30 20 40 x 50 30 If the mean of this distribution is 24. 29. calculate the value of x.7. (ii) 50. 11. 19. Score Frequency 10 50 20 70 x 20 40 30 50 30 If the mean of the distribution is 26. (ii) mode. 512.5. what is the range of values of x if the median is (i) 40. (i) Find the mean of the following set of numbers: 496. 493. 13. 507. Find the (i) mean. (iii) 60? Page 2 of 3 . 12.5. calculate the value of x. what is the range of values of x? (iv)It is discovered that the frequency of the last column is an error. 500. 35. 520 (ii) What is the median? (iii) What is the mode? 8. 9. 38. (iii) median of the following set of numbers: 19.

14. (ii) 75. Score Frequency 40 6 60 x 90 9 In this distribution of scores. what is the range of values of x if the median is (i) 65. (iii) 90? 15. (ii) 60? End of Practice Page 3 of 3 . what is the range of values of x if the median is (i) 60. Score Frequency 40 9 60 x 90 9 In this distribution of scores.
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