What is the missing number? 9/21 ?/105 A. 5 B. 45 C. 89 D. 93
2 answers:
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Answer:
1330 rounds of meetings
Step-by-step explanation:
You have a total of 21 people, and they all want to meet with each other in groups of 3. This means we are dealing with a combination problem, where combination is the selection of items in which order does <em>not</em> matter.
Formula for combination:
ₙCᵣ =
where <em>n</em> is the total number of objects (in this case, total number of people: 21), and r is the sample set (in this case, groups: 3).
We plug in and get:
->
-> 1330 different meetings for everyone to meet with each other in groups of 3.