Mysql query help

Hi, can anyone help me solve this please?

I need a query that gives me the category_id and the average number of actors by film of that category. So for example, for category 1 I want the division of 363 by 64. For category 2 I want the division of 361/66 and so on,

Thank you in advance

microsoft sql server forum here but here is a stab you would have to change it to fit MySQL

select category_id, count(actor_id)/film_count as brunomars
 natural join (
 select count(film_id) as film_count, catefory_id
 from film group by catefory_id
 ) hollywood 
from film natural join film_actor group by catefory_id