NIMCET 2014 Question Paper with solutions

Question : 11 of 120

Marks: +1, -0

In a group of 200 students, the mean and standard deviation of scores were found to be 40 and 15, respectively. Later on it was found that two scores 43 and 35 were misread as 34 and 53, respectively. The corrected mean of scores is

40.95
39.0
39.95
43

Validate

Solution:

We have,
Total number of students, n = 200
Combined mean,

x↖{-}

= 40
Misread data

(x_1,x_2)

= 34 , 53
Correct data

(x_3,x_4)

= (43 , 35)
∴ correct mean =

{x↖{-}n-(34+53)+(43+35)}/{200}

{200×40-87+78}/{200}

{7991}/{200}

= 3995

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