Soru

Zorluk: OrtaCombinations and Group Selections

A university research department must select a 4-member committee from a group of 6 biologists and 4 chemists. If the committee must contain at least 1 biologist and at least 1 chemist, how many different 4-member committees can be formed?

Cevap: 194

Cevap

194
Using complementary counting, the total number of ways to pick 4 members out of 10 is 210. The scenarios that break the rule are committees with all biologists (15 ways) or all chemists (1 way). Subtracting these 16 restricted selections from 210 results in 194 valid committees.

Adım Adım Çözüm

1
Find total unrestricted combinations
210 total committees
Choosing any 4 people out of the pool of 10 without restrictions yields 10C4 = 210.
2
Calculate restricted/invalid cases
16 invalid committees
All-biologist groups account for 6C4 = 15 combinations, and all-chemist groups account for 4C4 = 1 combination.
3
Apply complementary counting
194 valid committees
Subtracting the 16 invalid combinations from the total 210 combinations gives 194.

Anahtar Kavram

Combinations with Restrictions (Complementary Counting)
Bu soruyu puanla