Committee from officers and jawans (at least one officer): From 4 officers and 8 jawans, how many 6-person committees include at least one officer?

Aptitude Permutation and Combination Difficulty: Easy
Choose an option
  • A
    896
  • B
    986
  • C
    886
  • D
    996

Answer

Correct Answer: 896

Explanation

Introduction / Context:We must count 6-person committees that include at least one officer. The complement (no officer) is easier to compute and subtract from the total committees possible.

Given Data / Assumptions:Total people = 12 (4 officers + 8 jawans); committee size = 6.

Concept / Approach:Total − (no officer). No-officer committees must be formed entirely from jawans.

Step-by-Step Solution:

Total committees = C(12, 6) = 924No-officer committees = C(8, 6) = 28Required = 924 − 28 = 896

Verification / Alternative check:Summing by officer count (1 to 4) reproduces 896.

Why Other Options Are Wrong:986, 886, 996 are off by ignoring the complement or miscomputing combinations.

Common Pitfalls:Accidentally allowing 0 officers; arithmetic slips on C(12,6) or C(8,6).

Final Answer:896

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