Question

Arithmetic mean of marks (out of 25) scored by 10 students was 15. One of the student, named Karishma enquired the other 9 students and find the deviations from her marks are noted as −8,−6,−3,−1,0,2,3,4,6. Find Karishma's marks?​

Answer 1

Krishna's marks x marks

so...

xˉ=15

xˉ=15n=10

xˉ=15n=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+3=10x

x=150/10=15.3 marks

Krishna scored 15.3 marks.

hope it helps you sis...