A random sample M1, M2,M3...M8 is taken from a population with unknown mean x. For each of the following, state wether or not it is a statistic, giving your reasons:

a) (M3+M8)/2

b) (Summation of Mi)/n

3 answers

(Summation of Mi)/n is an approximation of the mean, much better than the first.
So a is not a statistic and b is.
https://www.jiskha.com/questions/1814615/a-random-sample-m1-m2-m3-m8-is-taken-from-a-population-with-unknown-mean-x-for-each-of