• # question_answer The mean of 10 observations is$5.5$. When one new observation is included in the data set, the mean of the observations becomes$6.0$. What is the value of new observation that was added to the data set? A)  11                  B)  10            C)  12                  D)  13

(a): Sum of 10 observations $=10\times 5.5=55$with one more observation, sum of 11 observations $=11\times 6=66$ $\therefore$  11th observation (new observation) $=66-55=11$