Pigeonhole Principle Statements

CMAT 2023 · Quantitative Techniques & Data Interpretation · Medium · Permutation and Combination

Given below are two statements:

Statement I: A bag contains 10 white and 10 red face masks which are all mixed up. The fewest number of face masks you can take from a bag without looking and be sure to get a pair of the same color is 3.

Statement II: The minimum number of students needed in a class to guarantee that there are at least 6 students whose birthdays fall in the same month, is 61.

In the light of the above statements, choose the most appropriate answer from the option given below:

  1. A.

    Both Statement I and Statement II are correct

  2. B.

    Both Statement I and Statement II are incorrect

  3. C.

    Statement I is correct but Statement II is incorrect

  4. D.

    Statement I is incorrect but Statement II is correct

Answer

A

Explanation

Statement I: Since there are 2 colors, by Pigeonhole Principle, drawing 3 masks guarantees at least 22 masks of the same color. Thus, Statement I is correct.

Statement II: To ensure at least 6 students share a birthday month, consider worst case where 5 students are born in each of the 12 months, totaling 5×12=605 \times 12 = 60 students. Adding 1 more student ensures at least 6 birthdays fall in the same month. So minimum students needed =60+1=61= 60 + 1 = 61. Statement II is correct.

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