Look up grade from a table of values

Hi

apologies if this is not in the correct forum
I have limited knowledge of excel and some of the SUM functions. I have a risk grade that I am trying to automate in excel.
The variances are as follows:

0-100 = R1
100-125 = R2
125-225 = R3
225-325 = R4
325-425 =R5
425-525 = R6


So once the final score (left hand column) has been calculated, can I insert a sum into excel to automatically populate the cell with the overall risk grade (right hand column) ??

Thanks in advance

Scotia