Question
Asked Nov 4, 2019
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How many different 16- bit strings contain exactly 4 1s? 

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Expert Answer

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Step 1

According to the given information the total number of bits in a string is 16.

It is needed to calculate the number of bits that should contain exactly 4 one’s.

So, n = 16 and r = 4

So, the number of bits can be calculated by:

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16 4

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Step 2

The formula used to calculate above expression is:

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п! "С, r(п-г)!

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Step 3

Now, use the formul...

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16! 16 CA 4(16-4 16! 4!(12!) 16x 15 x 14x 13 x 12! (using n! = nx(n-1)x (n-2)x. 4x 3x 2x 1x 12! 16x 15 x 14x 13 4x3x2x1 = 4x5x 7x 13 =1820

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