Question

arithmetic mean of marks (out of 25) scored by 10 students was 15.one of the students named karishma enquired the other 9 students and find the deviations from her marks are naoted as -8,-6,-3,-1,0,1,2,3,4,6.find karishma marks

Answer 1

Given,

Total no. of students(n) = 10

Average Marks Obtained(x)= 25

To find,

Marks obtained by Karishma marks.

Solution,

Let Krishna marks x marks.

x  = 15

n= 10

∑x = x + (x − 8) + (x − 6) +(x − 3) + (x − 1) + (x) + (x + 2) + (x + 3) + (x + 4) + (x + 6)     = 10x − 3

⇒15 =( 10x − 3)/10

⇒150 = 10x-3

⇒10x = 153

       x = 153/10

      x = 15.3

So, Krishna scored 15.3 marks.