The TRIMMEAN function gives you the average of the interior of a
distribution, where you cut x% from both the top and the bottom.

Is it possible to easily modify the percentages, so I could find the
average between specific percentiles? Say, finding the average of the
values between the 20th and 40th percentiles, rather than just trimming
out on either end? (In this example, I know I could use PERCENTILE to
just find the 30th percentile to get close, but in the data I'm using
it would be better to get an average of a group.)

Thanks very much,

Andrew