Question

The mean of 12 observations is 20 if every observation is decreased by 2 find the new mean

• A. $18$
• B. $16$
• C. $12$
• D. $-10$

Answer 1

The correct option is A $18$

No .of observations $12$

Mean of observations $20$

Sum of observations $12\times 20=240$

Every observation is decreased by $2$ so total decrease is $2\times 12=24$

So the sum of observations is $240-24=216$

Mean $=\frac{216}{12}=18$