Question 752836
Let the score on the missing paper be x.
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If he lost score of 1 student and has score of other 4, it means he has a total of 5 students!

Mean (Average) = Total Score / Number of Students.

We have,
Mean (Average) = 88.2 = 882/10;
Total Score = (93+86+86+84)+ x = 349+x
Number of Students = 5;

{{{(882/10) = (349+x)/5}}}

Cross Multiply
{{{(882*5)=10*(349+x)}}}
{{{4410=3490+10x}}}
{{{4410-3490=10x}}}
{{{920=10x}}}
Divide through by 10:
{{{(920/10)=(10x/10)}}}
{{{92=x}}}

Therefore, missing score is 92