What I want to accomplish is that I want to summarize the data in the
sheets "data" under some conditions?

For example I want to know how many customers have balance below 4000
and how many of them have balance above 5000, etc

So I have a set of conditions in column B in "summary" sheet, < 4000,

5000

in column C, another variable =0, =1 etc

...........

In column O, is the sum of customers satisfy my conditions in column B
to P.

How can I do this? Thanks.