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2. Marks (out of 50 ) obtained in Mathematics by 100 students is given in the followingtable. Find the mean by direct methodMarksD-1010-2020-3030-4040-502010203020No ofstudents |
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Answer» ong>Answer: Step-by-step explanation: Direct method
size
x
f
0-10
5
20
100
10-20
15
20-30
25
40
1000
30-40
35
36
1260
40-50
45
20
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 |
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