Storing ranges in a table

I work for a telemarketing company. They pay their reps based on the rep's total calltimes.
I have the following payrates that I need stored in a table:

Level PayRate Range
1 $6.15 1st 20 hours of dialing
2 $8.50 From 21st hour of dialing to the 90th day of dialing
3 $10 From the 91st day of dailing


How can I break up the ranges into a table? I will have the rep's total calltime and based on that I need to figure out the payrate level.

Thanks,
Ninel

You could create a table with the following columns:

Level,
PayRate,
Min_Time
Max_Time

Using your example, the table might look like this (times in minutes and assumes a day as 24 hours):
LEVEL PayRate Min_Time Max_Time
1 $6.15 0 1199
2 $8.50 1200 129599
3 $10.00 129600 999999999999
Whenever the total time falls between the min and max, use the payrate assigned.

I hope you get some ideas. Let me know if you need more help.