Manually adjust grouping in pivot table

I have two columns - one with values 1-15 - and the one other with text values. What I would like to do is to create three ranges of the number values. 1-3, 4-8, 9-15 and then put the text values in the correct range they've been associated with.

A pivot table with grouping sort of does the trick and if I put in 5 in the "by" field I get three ranges - but they're not what I want. Is it possible to manually change to this to filter it by the range I want?

Thanks.

Yeah, that worked the way I wanted. Thanks! But it can be a bit cumbersome if you have a lot of rows. But it does the trick.