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Q.
If the mean of four observations is 20 and when a constant c is added to each observation, the mean becomes 22. The value of c is :
Statistics
Solution:
Mean of four observations = $20$
$\therefore $ total observations = $20 \times 4 = 80$
When add c in each observation total observation will be $80 + 4c$, then new mean = $22$
$\therefore $ According to the question,
$80 + 4c = 22 \times 4$
$\Rightarrow \:\: 80 + 4c = 88$
$\Rightarrow \:\: 4c = 8 \Rightarrow c = 2$