How many bit strings of length n contain more 0’s than 1’s?

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To solve this, I think we need to use combinatorial reasoning.=

Consider a bit string of length ( n ). There are ( 2^n ) possible bit strings of this length because each bit can independently be either 0 or 1.

Let's denote:

  • ( k ) as the number of 0's in the string
  • ( n ) as the length of the bit string

This means:

  • For ( k = 0 ), there's only one possibility, which is all bits being 1. So, there's 1 string.
  • For ( k = 1 ), there are ( n ) possibilities because there are ( n ) positions where the single 0 can be placed in the string.
  • For ( k = 1 ), there are ( \binom{n}{1} ) possibilities because there are ( n ) positions where the single 0 can be placed in the string.
  • For ( k = 2 ), there are \( \binom{n}{2} \) possibilities because we're choosing 2 positions out of ( n ) for the 0's to occupy. -For ( k = 3 ), there are ( \binom{n}{3} ) possibilities, and so on, until ( k = \lfloor \frac{n}{2} \rfloor )

The asnwer: total number of bit strings with more 0's than 1's is the sum of the possibilities for each ( k ) from 0 to ( \lfloor \frac{n}{2} \rfloor ).

Is this right?