For any evenly-spaced set of numbers, the median and the mean will be the same. To calculate the median (and therefore the mean), all we have to do is this:
(first + last)/2Given that all two-digit positive integers have a spacing of one, then these qualify as evenly-spaced. The first two-digit positive integer is 10 and the last is 99.
Here we only need to apply
(first + last)/2 = (10+99)/2 = 109/2 =
54.5. Answer C.
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