Chapter 24: Problem 98
Four tickets marked \(00,01,10,11\), respectively are placed in a bag. A ticket is drawn at random five times, being replaced each time. The probability that the sum of the numbers on tickets thus drawn is 23 is (A) \(\frac{25}{256}\) (B) \(\frac{100}{256}\) (C) \(\frac{231}{256}\) (D) none of these
Short Answer
Step by step solution
Understanding the Problem
Converting Binary to Decimal
Total Number of Outcomes
Possible Combination Sum to 23
Conclusion on Possibility
Determining the Probability
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Binary Numbers Unveiled
Each position in a binary number represents a power of 2, starting with 2 raised to the power of 0 on the furthest right. For example, the binary number 1101 is calculated as follows:
- The rightmost digit, 1, represents 2^0 which is 1.
- The next digit to the left, 0, represents 2^1 which is 2, but because it's 0, it adds 0 to the total.
- The next digit is 1, representing 2^2, which is 4.
- The leftmost digit, another 1, represents 2^3, which is 8.
Decimal Conversion Made Easy
To convert a binary number to decimal:
- Write down the binary number.
- Starting from the right, multiply each binary digit by the power of 2 that corresponds to its position.
- Sum all these values to get the decimal equivalent.
- The rightmost 0 represents 0 times 2^0, which is 0.
- The next 1 represents 1 times 2^1, which equals 2.
- The following 0 represents 0 times 2^2, adding 0.
- The leftmost 1 represents 1 times 2^3, which is 8.
By adding them, 0 + 2 + 0 + 8, the decimal number is 10. Converting accurately is imperative for calculating sums when dealing with binary numbers.
Exploring Combinatorics
When you draw items with replacement, like in our exercise, each draw is independent. Hence, the formulas for combinations or permutations need to adapt to these conditions.
- For a single event with multiple outcomes, such as drawing a ticket, the total number of possible outcomes is raised to the power of the number of events (repeated draws).
- In the exercise example, there are four tickets and five draws, resulting in 4^5, or 1024, possible outcomes.
- Combinatorics also allows us to calculate the probability of certain combinations, but only when they make sense, such as sums within possible number ranges.