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The image shows an office key holder where 8 different keys

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The image shows an office key holder where 8 different keys

by fskilnik@GMATH » Mon Feb 04, 2019 1:56 pm
Image

<b>GMATH</b> practice question (Quant Class 18)

The image shows an office key holder where 8 different keys must be placed (one key per square).
If the two main keys must be placed in the blue squares, in how many ways can all the keys be placed in the key holder?

(A) 360
(B) 720
(C) 1440
(D) 2880
(E) 4320

Answer: [spoiler]____(C)__[/spoiler]

Source: https://gmath.net
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by fskilnik@GMATH » Tue Feb 05, 2019 5:15 am
fskilnik@GMATH wrote:Image

<b>GMATH</b> practice question (Quant Class 18)

The image shows an office key holder where 8 different keys must be placed (one key per square).
If the two main keys must be placed in the blue squares, in how many ways can all the keys be placed in the key holder?

(A) 360
(B) 720
(C) 1440
(D) 2880
(E) 4320

Source: https://gmath.net

? = # of 8-keys placing

? = P2 (main keys) * P6 (other keys) = 2! * 6! = 2 * 720 = 1440.


The correct answer is therefore (C).


We follow the notations and rationale taught in the GMATH method.

Regards,
Fabio.
Fabio Skilnik :: GMATH method creator ( Math for the GMAT)
English-speakers :: https://www.gmath.net
Portuguese-speakers :: https://www.gmath.com.br
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