Hi I was wondering how to set up a formula based on certain date criteria that will cause a set of values to change if the date is greater than the date criteria.

Assuming that the date criteria is 01/02/2010, and any date (column a) after this would cause the set of values (column b) to increase by 5%.

example.

A B
01/01/2010 10
01/02/2010 5
01/03/2010 2
01/04/2010 1

do i use =sumproduct as the formula and how would i set it up. Thanks in advance.