What proportion of customers who have accounts at the Prague branch are female?
Female refers to gender = 'F'; Percentage of female clients in Prague branch = count[female clients with accounts in Prague branch / count(clients with accounts in Prague branch)] * 100%; A3 may contain information about Prague
SELECT CAST(SUM(T2.gender = 'F') AS REAL) / COUNT(T2.client_id) * 100 FROM district AS T1 INNER JOIN client AS T2 ON T1.district_id = T2.district_id WHERE T1.A3 = 'Prague'