Find the mean height of the students given in table.
Height in centimeters
Number of students
(Frequency)
101 – 110
111 – 120
121 – 130
131 – 140
141 – 150
151 – 160
8
15
24
40
10
3
Total
100
It appears that the mean value will lie the class 131-140. The mid value (for class mark) of this interval is 135.5. Take a = 135.5, the width of each interval is c = 10.
Height (cm)
Mid-class (x_i)
Frequency (f)
x_i f_i
u=(x-135.5)/10
u f
101-110
105.5
844
-3
-24
111-120
115.5
1732.5
-2
-30
121-130
125.5
3012
-1
131-140
135.5
5420
0
141-150
145.5
1455
1
151-160
155.5
466.5
2
6
N =100
∑〖x_i f_i=12930〗
-
∑〖u f= -62〗
total answers (1)
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It appears that the mean value will lie the class 131-140.
The mid value (for class mark) of this interval is 135.5.
Take a = 135.5, the width of each interval is c = 10.
Height (cm)
Mid-class (x_i)
Frequency (f)
x_i f_i
u=(x-135.5)/10
u f
101-110
105.5
8
844
-3
-24
111-120
115.5
15
1732.5
-2
-30
121-130
125.5
24
3012
-1
-24
131-140
135.5
40
5420
0
0
141-150
145.5
10
1455
1
10
151-160
155.5
3
466.5
2
6
Total
N =100
∑〖x_i f_i=12930〗
-
∑〖u f= -62〗