11. The following table shows distribution
of marks obtained by 60 students in
Economics test. Calculate the arithmetic
mean using assumed mean method.
Your answer
Answers
Answer:
10th
Maths
Statistics
Mean of Grouped Data
The following table shows t...
STATISTICS
The following table shows the marks scored by 140 students in an examination of a certain paper:
Marks: 0-10 10-20 20-30 30-40 40-50
Number of students: 20 24 40 36 20
Calculate the average marks by using all the three methods: direct method, assumed mean deviation and shortcut method.
MEDIUM
Share
Study later
ANSWER
Direct method
size
x
f
xf
0-10
5
20
100
10-20
15
24
360
20-30
25
40
1000
30-40
35
36
1260
40-50
45
20
900
mean =
∑f
∑fx
=
140
3620
=25.857
Assumed mean method
size
x
u=x-25
f
uf
0-10
5
-20
20
-400
10-20
15
-10
24
-240
20-30
25
0
40
0
30-40
35
10
36
360
40-50
45
20
20
400
mean =A+
∑f
∑fu
=25+
140
120
=25.875
Step deviation method
size
x
d=x-25
u=(x-25) / 10
f
uf
0-10
5
-20
-2
20
-40
10-20
15
-10
-1
24
-24
20-30
25
0
0
40
0
30-40
35
10
1
36
36
40-50
45
20
2
20
40
mean =A+h×
∑f
∑fu
=25+10×
140
12
=25.875