To see the cache hit ratio for a single query, use set statistics io on to see the number of logical and physical reads, and set showplan on to see the I/O size used by the query.
To compute the cache hit ratio, use this formula:
With statistics io, physical reads are reported in I/O-size units. If a query uses 16K I/O, it reads 8 pages with each I/O operation.
If statistics io reports 50 physical reads, it has read 400 pages. Use showplan to see the I/O size used by a query.