单选题：Assume that there are 10000 documents in the database, and the s

Assume that there are 10000 documents in the database, and the statistical data for one query are shown in the following table. One metric for evaluating the relevancy of the query is F-α score, which is defined as ((1+ α)∙(precision*recall))/(α∙precision+recall). Then the F-0.5 (α=0.5) score for this query is:


| | **Relevant** | **Irrelevant** |
| -------- | -------- | -------- |
| **Retrieved** | 4800 | 1200 |
| **Not Retrieved ** | 3200 | 800 |



@[B](1)

A. 0.80
B. 0.72
C. 0.60
D. 0.65



A.0.80
B.0.72
C.0.60
D.0.65


答案：B