Question

A box contains 7 red, 6 white and 4 blue balls. How many selections of three balls can be
made so that none is red?​

Answer 1

Answer:

7 red means 1r, 2r, 3r, 4r, 5r, 6r, 7r.

6 white means 1w, 2w, 3w, 4w, 5w, 6w.

4 blue means 1b, 2b, 3b, 4b.

sample space n(S)=17

event A=n(A)=10.

I think you will satisfy with this answer