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From a box of 10 lightbulbs, you are to remove 4. How many d

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From a box of 10 lightbulbs, you are to remove 4. How many d [#permalink] New post 30 May 2019, 11:24
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From a box of 10 lightbulbs, you are to remove 4. How many different sets of 4 lightbulbs could you remove?

[Reveal] Spoiler: OA
210


Math Review
Question: 9
Page: 297
Difficulty: medium

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Re: From a box of 10 lightbulbs, you are to remove 4. How many d [#permalink] New post 31 May 2019, 05:07
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Carcass wrote:
From a box of 10 lightbulbs, you are to remove 4. How many different sets of 4 lightbulbs could you remove?

[Reveal] Spoiler: OA
210


Math Review
Question: 9
Page: 297
Difficulty: medium


In this case, the order in which we select the 4 bulbs does not matter.
For example, selecting bulb A, then bulb D, then bulb E, and then bulb H, is the SAME as selecting bulb H, then bulb D, then bulb A, and then bulb E
So, we can use COMBINATIONS.

We can select 4 bulbs from 10 bulbs in 10C4 ways

10C4 = (10)(9)(8)(7)/(4)(3)(2)(1) = 210

Answer: 210

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Brent
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Re: From a box of 10 lightbulbs, you are to remove 4. How many d   [#permalink] 31 May 2019, 05:07
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From a box of 10 lightbulbs, you are to remove 4. How many d

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