#### The mean and SD of the marks of 200 candidates were found to be 40 and 15.Later it was discovered that a score of 40 was wrong read as 50.The Correct mean and SD are: Option 1) Option 2) Option 3) Option 4) None of these

As we discussed in concept

Standard Deviation -

If x1, x2...xn are n observations then square root of the arithmetic mean of

- wherein

where  is mean

Total Sum:=:40x200=8000

Now new sum:=:8000-50+40=8000-10=7990

So S.D = 14.98

as S.D =

Option 1)

This option is incorrect.

Option 2)

This option is correct.

Option 3)

This option is incorrect.

Option 4)

None of these

This option is incorrect.