The mean of a set of Grouped Data
Find the mean of the following grouped data.
Score Midpoint Frequency Sum of data #2 :
0−4 2 4 Determine
5−9 7 5
10−14 12 9 the
15−19 17 4 sum
20−24 22 2 of
25−29 27 6 data 51
The mean of a set of Grouped Data
Find the mean of the following grouped data.
Score Midpoint Frequency Sum of data 52
0−4
5−9 2×4 8
10−14 7×5 35
15−19 12 × 9 108
20−24 17 × 4 68
25−29 22 × 2 44
27 × 6 162
Find the mean of the following grouped data.
Number of frequency
4+5+9+4+2+6
= 30
Mean 53
8 + 35 + 108 + 68 + 44 + 162 425
30 = 30
= 14.17
TP 2 Calculate the mean for the time taken to
do revision by a few pupils.
Time 234 5 54
taken to
Time (hour)
do
revision
1
2×7 3×5 Number of frequency
1×4 4×3
5×14 + 7 + 5 + 3 + 1
= 20
4 + 14 + 15 + 12 + 5= 50
20 20
= 2.5
55
Measure of Central Tendency
Mode Median Mean
众数 中位数 平均数
The most appropriate measure
for central of tendencies
56
Mode the number that appears the most
5 55 6 7 7 14
The mode is useful when
the most popular
data or item is required.
57
Median the number in the middle
5 556 7 7 34
The median is useful for sets
of data containing
extreme values.
58
Mean the sum of the data divided
by the number of data
(5+5+5+6+7+7+14) / 7 = 7
The mean is most commonly used
average values.
It takes into account the value of
every data. 59
Determining the type of
measure of central tendencies
that is suitable
for the situations given.
60
The stems and leaf plot below shows
the weight of marbles in 10 plastic jars.
TP 3 50g, 56g, 58g, 61g, 61g,
64g, 67g, 72g, 76g, 79g
Solution:
Mean because there
is no extreme value
in the set of data
61
The pictograph below shows the flavour of
ice cream favoured by kindergarten students.
Solution:
Mode because
this is a category
data and it will
determine the
favourite item.62
The line graph below shows the production of
palm oil in a factory for 5 months. TP 3
70 Solution:
60 Mean –
50 50 40 because there is
no extreme value
in the set of data.
63
The table below shows the number of hours spent
browsing the Internet by Form 2 Melor students.
Solution: Mean – because there is
no extreme value in the set of data.
64
The dot plot below shows the time taken in
hours when 10 drivers made a trip from Ipoh to
Melaka by car. TP 3
Solution:
Median−
because there is
an extreme value
in the set of data.
65
The pie chart below shows the favourite fruits
of the students of Form 2 Gemilang. TP 3
Solution:
Mode − because this
is a category data and
it will determine the
favourite item.
66
The bar chart below shows time taken in hours
for some students to do revision in a day. TP 3
Solution:
Mean –
because there is
no extreme value
in the set of data.
67
The stem-and-leaf plot shows the volume of
chemical solution, in ml, for 19 different bottles.
TP 3
Solution:
Median−
because there is
an extreme value
in the set of data.
68