Binary-answer test sequences: A test has 10 questions, each answered True (T) or False (F). Every candidate answers all questions. How many distinct T/F answer sequences are possible?

Difficulty: Easy

Correct Answer: 1024

Explanation:


Introduction / Context:
Each question admits 2 choices (T or F), independently across questions. Counting sequences of independent binary choices leads to a simple power rule, 2^n for n questions.


Given Data / Assumptions:

  • n = 10 questions.
  • Choices per question = 2 (T or F), independent.
  • Every candidate answers all questions.


Concept / Approach:

  • Use the multiplication principle: 2 * 2 * … * 2 (10 times) = 2^10.


Step-by-Step Solution:

Number of sequences = 2^10 = 1024


Verification / Alternative check:
Binary coding analogy: each sequence corresponds to a 10-bit string; total 10-bit strings = 2^10 = 1024.


Why Other Options Are Wrong:

  • 512 = 2^9; too small.
  • 20 and 40 are unrelated to 2^10.


Common Pitfalls:

  • Treating “questions” as dependent when they are independent.


Final Answer:
1024

More Questions from Permutation and Combination

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