Use the shortcut method to find the mean of given data.
Let the assumed mean be (A) = 2,
The deviation of values xi from assumed mean be di = xi – A.
Now to find the mean:
First multiply the frequencies in column (ii) with the value of deviations in column (iv) as fidi.
Now add the sum of all entries in column (iv) to obtain
and the sum of all frequencies in the column (ii) to obtain
where, N = total number of observations
⇒ 3(72 + k) = -260 + 20k
⇒ 216 + 3k = -260 + 20k
⇒ 476 = 17k
⇒ k = 28
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