Question: On average, one cubic inch of Granma's cookie dough contains 2 chocolate chips and 1 marshmallow.
a) Granma makes a cookie using three cubic inches of her dough. Find the chance that the cookie contains at most four chocolate chips, state your assumptions.
b) Assume the number of marshmallows in Granma's dough is independent of the number of chocolate chips. I take three cookies, one of which is made with tow cubic inches of dough, the other two with three cubic inches each. What is the chance that at most I of my cookies contains neither chocolate chips nor marshmallows?