IPMAT Rohtak 2020 (QA) - A box contains 2 white shirts, 3 black shirts, and 4 red shirts. In how many ways can 3 shirts be drawn from the box, if at least one black shirt is to be included in the draw? | PYQs + Solutions | AfterBoards
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IPMAT Rohtak 2020 (QA) PYQs

IPMAT Rohtak 2020

Modern Math
>
Permutation & Combination

Conceptual

A box contains 2 white shirts, 3 black shirts, and 4 red shirts. In how many ways can 3 shirts be drawn from the box, if at least one black shirt is to be included in the draw?

Correct Option: 3
Total ways to select 3 shirts with at least one black shirt \newline= Total ways to select 3 shirts - Ways to select 3 shirts without any black shirt
Total ways to select 3 shirts = 9C3^9C_3 = 84
Ways to select 3 shirts without black = 6C3^6C_3 = 20
(selecting from only white(2) and red(4) shirts)
Therefore, required ways = 9C3^9C_3 - 6C3^6C_3\newline= 842084 - 20\newline= 6464
Therefore, there are 64 ways of picking out atleast 1 black shirt.

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