arrange them from least to greatest form
250 cal., 270 cal., 280 cal., 280 cal., 320 cal.,
Mean =

(5 because there is a total of 5 fast food restaurants' hanburgers)
=
Mean = 280 calories
Median = The number exactly in between,
In midst of these numbers, 280 is in the mid-way
Median = 280 calories