I have the follwing worksheet"

Date Rate Qty
2:06:56 PM 199.5 116
2:06:49 PM 199.5 343
2:06:40 PM 199.5 226
2:06:28 PM 199.5 48
2:06:20 PM 199.4 162
2:06:11 PM 199.5 95
2:06:04 PM 199.4 449
2:05:58 PM 199.6 1488
2:05:40 PM 199.5 9
2:05:40 PM 199.5 9
2:05:37 PM 199.4 161
2:05:28 PM 199.6 101
2:05:23 PM 199.35 4605
2:05:15 PM 199.5 5926
2:05:06 PM 199.6 217
2:04:57 PM 199.6 3
2:04:52 PM 199.75 207
2:04:44 PM 199.6 4180
2:04:39 PM 199.8 75
2:04:32 PM 199.55 2277
2:04:20 PM 199.7 194
2:04:13 PM 199.5 4280
2:04:09 PM 199.7 780
2:03:58 PM 199.7 108
2:03:49 PM 199.7 10
2:03:46 PM 199.7 3006
2:03:32 PM 199.75 1471
2:03:22 PM 199.6 217
2:03:16 PM 199.7 815
2:03:10 PM 199.7 271
2:03:04 PM 199.6 400
2:02:54 PM 199.75 50
2:02:48 PM 199.75 168
2:02:39 PM 199.75 210
2:02:24 PM 199.75 257
2:02:19 PM 199.5 1067
2:02:12 PM 199.85 2055
2:01:59 PM 199.55 2
2:01:53 PM 199.95 114
2:01:48 PM 199.4 4544
2:01:43 PM 200 143
2:01:35 PM 200 736
2:01:28 PM 199.9 212
2:01:20 PM 199.8 325
2:01:12 PM 199.5 10100
2:01:03 PM 199.8 2873
2:00:58 PM 199.8 492
2:00:44 PM 200.2 551
2:00:37 PM 199.85 2965
2:00:28 PM 199.85 1429
2:00:20 PM 199.65 474
2:00:13 PM 199.9 2226
2:00:02 PM 200 168
1:59:57 PM 199.65 33
1:59:50 PM 199.6 47

I would like to calculate the weighed average rate( rate*qty/total qty
durig a period) for different periods say 2.00 pm to 2.01 pm, 2.01pm
to 2.02 pm etc. Is there a way to do this by using
database(dsum,daverage) functions. What will be the content of the
criterion range?

Or is there any other way of solving this. Thanks ln advance