Explanation
1. Analyzing the Choices for Each Question
For every single question in the paper, a student has 2 options:
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Attempt the question.
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Do not attempt the question.
2. Calculating Total Possible Outcomes
Since there are 50 questions and each question has 2 options, the total number of ways to deal with the entire paper is:
Total ways=2×2×2×… (50 times)
3. Understanding the "One or More" Constraint
The 250 total ways include every possible combination, including the single case where the student attempts zero questions (leaves all 50 questions blank).
The problem specifically asks for the number of ways to attempt one or more questions. This means we must subtract the "all blank" case from the total.
4. Final Calculation
Ways to attempt at least one question=(Total ways)−(Ways to attempt zero questions)
Conclusion
This follows the formula for finding the number of non-empty subsets of a set with n elements, which is 2n−1.
Correct Answer: 250−1