In how many ways 4 balls can be picked from 6 black and 4 green colored balls such that at least one black ball is selected?

Step-by-step solution

All possible cases if at least one Black ball is selected are, 1 B   3 G ,   2 B   2 G ,   3 B   1 G ,   4 B   0 G Then total number of ways are, = C 1 6 × C 3 4 + C 2 × 6 C 2 4 + C 3 × 6 C 1 4 + C 4 6 = 6 × 4 + 15 × 6 + 20 × 4 + 15 = 209