If the mean of the following data is 7.5,then find the value of A

marks NO.OF.students
5 3
6 10
7 17
8 A
9 8
10 4

1
5 and 3 are separate or both are one number 53
5 is x and 3 is f
Maybe the answer comes out to be 18, right?
no
There is no problem with the question.It's absolutely correct

Answers

2014-12-11T14:39:17+05:30
Marks                 freq.
 5                           3
6                           10
7                          17
 8                          A
9                           8
10                          4

Mean=Σfx/Σf
7.5=15+60+119+8A+72+40/42+A
⇒7.5=306+8A/42+A
⇒315+7.5A=306+8A
⇒0.5A=9
⇒A=9/0.5=18

So A=18

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