How to choose pixel values according to each land cover class?

Question

I would like to do following steps using two types of images (precpitation and Land cover image):

1. select pixel values of precipitation image within each land cover classes
2. calculate total amount of precipitation of each land cover classes

Could you please tell me the tools I use and the steps I need to follow in ArcGIS, ENVI, or ERDAS.

Answer 1

In ArcGIS use the zonal statistics tool.