Sets numerical

[urvashi]

A box contains 100 balls  28red,17blue,21green,10white,12black,12yellow . The smallest no n such that any n balls drawn  from the box will contain atleast 15 balls of the same colour        a.73 b.77 c.81 d.85

[Amit Goyal]

77

[urvashi]

Thank you sir if you could please explain how you came to the answer i am having trouble with it

[Amit Goyal]

Think about the worst case:
14 red, 14 blue, 14 green, 10 white, 12 black, 12 yellow

Total = 76 balls

Any additional ball will necessarily increase the count of at least one of the three (red, blue and green) to 15.

[urvashi]

Thank you sir