- Option : D
- Explanation : (D) The mean of n observation is m.

if m^{2}- m + 1 is added to cach observation, then the mean will increase by m^{2}- m + 1,

Then new mean = m + m^{2}- m + 1

= (1 + m^{2})

- Option : B
- Explanation : Sum of production during

odd years (2009, 2011, 2013)

= 90 + 105 + 75 = 270 tonne.

Sum of production during even years

(2010,2012,2014)

=110 + 130 + 120 = 360 tonne.

Let the sum of production during odd

years is x times that of the even years.

270 = x × 360 => x = 270/360.

x =0.75

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