JEE Math Practice Question
Let the mean and variance of the frequency distribution $$\begin{matrix} {x:} & {{x_1} = 2} & {{x_2} = 6} & {{x_3} = 8} & {{x_4} = 9} \\ {f:} & 4 & 4 & \alpha & \beta \\ \end{matrix} $$ be 6 and 6.8 respectively. If x3 is changed from 8 to 7, then the mean for the new data will be :
- A.4
- B.5
- C.$${{17} \over 3}$$
- D.$${{16} \over 3}$$
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