Four bags weigh 4, 6, 8 and 10 kilograms. What is the median weight?

Explication

With four values in order there is no single central one, so the median is the mean of the two weights in the middle, 6 and 8, which gives 7 kilograms. Picking 6 kilograms uses one of those two weights on its own and gives the other no say, which leaves the result off centre.