Math Problem Statement
How many bit strings of length 10 contain either 5 consecutive 0’s or 5 consecutive 1’s
Solution
To solve this problem, we need to count how many bit strings of length 10 contain either 5 consecutive 0's or 5 consecutive 1's.
Step 1: Use the Inclusion-Exclusion Principle
We will approach this problem using the Inclusion-Exclusion Principle.
Let:
- be the set of bit strings that contain 5 consecutive 0's.
- be the set of bit strings that contain 5 consecutive 1's.
We are asked to find the number of bit strings that belong to either or , which is given by:
Where:
- is the number of bit strings with 5 consecutive 0's,
- is the number of bit strings with 5 consecutive 1's,
- is the number of bit strings with both 5 consecutive 0's and 5 consecutive 1's.
Step 2: Count — Bit Strings with 5 Consecutive 0's
We need to count the number of bit strings of length 10 that contain at least one block of 5 consecutive 0's.
- If a block of 5 consecutive 0's appears, it can start at one of the positions 1 through 6 (because the block of 5 zeros must fit within the 10-bit string).
- Once we place this block, the remaining 5 bits can be filled freely with 0's or 1's.
Thus, for each starting position of the 5 consecutive 0's, there are ways to fill the remaining positions.
So, there are 6 possible positions for the 5 consecutive 0's, and for each position, there are ways to fill the remaining 5 bits.
Thus, the total number of bit strings with 5 consecutive 0's is:
Step 3: Count — Bit Strings with 5 Consecutive 1's
This is similar to counting bit strings with 5 consecutive 0's, but now with 5 consecutive 1's. By the same reasoning, the number of bit strings with 5 consecutive 1's is also:
Step 4: Count — Bit Strings with Both 5 Consecutive 0's and 5 Consecutive 1's
Now, we need to count how many bit strings of length 10 contain both 5 consecutive 0's and 5 consecutive 1's. These two blocks must overlap in some way.
There are only two ways for this to happen:
- The 5 consecutive 0's and 5 consecutive 1's are arranged such that they do not overlap (e.g., one block of 5 0's and one block of 5 1's).
- They must overlap in such a way that the remaining positions are filled in a manner that meets both conditions.
However, a bit string that contains both blocks must meet certain conditions to fulfill these patterns, and to keep things simple, this is difficult to resolve quickly with only basic guidance
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Math Problem Analysis
Mathematical Concepts
Combinatorics
Inclusion-Exclusion Principle
Bit Strings
Counting Principles
Formulas
|A ∪ B| = |A| + |B| - |A ∩ B|
2^n (for counting possibilities with free bits)
Theorems
Inclusion-Exclusion Principle
Suitable Grade Level
Grades 11-12
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