Histogram question.

Queries in PostgreSQL: 2. Statistics : Postgres Professional
<https://postgrespro.com/blog/pgsql/5969296>



SELECT sum(s.most_common_freqs[ array_position((s.most_common_vals::text::
text[]),v) ]) FROM pg_stats s, unnest(s.most_common_vals::text::text[]) v
WHERE s.tablename = 'boarding_passes' AND s.attname = 'seat_no';

*return 0.6762. *

SELECT sum(s.most_common_freqs[ array_position((s.most_common_vals::text::
text[]),v) ]) FROM pg_stats s, unnest(s.most_common_vals::text::text[]) v
WHERE s.tablename = 'boarding_passes' AND s.attname = 'seat_no' AND v >
'30C';

return *0.2127*

SELECT round( reltuples * ( 0.2127 -- from most common values + (1 - 0.6762
- 0) * (49 / 100.0) -- from histogram )) FROM pg_class WHERE relname =
'boarding_passes';

the above mentioned query, the part I don't understand is *49/100.*