Richard can make 8 dough balls in two hours. If the amount of time is directly proportional to the number of dough balls, how many hours have passed if he made 18 dough balls?

Well.. let’s see... It would take him 2 hours to make 8 dough balls... So, 1 hour would give him 4 and 1/2 hour would make 2... So, 4 hours would have him at 16 dough balls, then add a half hour to get 18 dough balls!! So, it’d take 4 and 1/2 hours to make 18 dough balls!

With a continuous thought process.