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?

Difficulty: Easy

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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