Why should the number of classes in a frequency distribution be between 5 and 20?

Seymour is twice as old as cassandra. if 16 is added to cassandra’s age and 16 is subtracted from seymour’s age, their ages become equal. what are their present ages? show !

The power generated by an electrical circuit (in watts) as a function of its current c (in amperes) is modeled by p(c)= -15c(c-8) what current will produce the maximum power?

5cakes cost 3.50 how much do 7 cakes cost