If ∑xifi = 306 + 8 A, ∑fi = 42 + A and Mean of the Data is 7.5. Find the value of A.
Answers
Answer:
Marks (x1) No of students (f1) x1f1
5 3 15
6 10 60
7 17 119
8 A 8A
9 8 72
10 4 0
Total 42+A 306+8A
Sum of frequency (f1) =42+A
Sum of f1x1 = 306+8A
Given mean is 7.5
Mean
x
ˉ
=
Σf
1
Σf
1
x
1
∴7.5=
41+A
306+8A
⇒306+8A=7.5(42+A)
⇒306+8A=315+7.5A
⇒8A−7.5A=315−306
⇒0.5A=9
⇒A=18