Comments on: Problems Based on Selection of Balls

By: Hemant More

Hemant More — Thu, 12 May 2022 12:53:51 +0000

In reply to Jairo.

20C2 = (20!)/[(2!) x (20-2)!]
20C2 = (20!)/[(2!)x (18!]
20C2 = 20 x 19 x (18!)/[(2 x 1)x (18!)]
20C2 = 10 x 19

Jairo — Wed, 11 May 2022 15:58:15 +0000

There’s a typo in most denominators. It’s 20×19 instead of 10×19. Thank you for the examples. Great and quick recap!