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A committee of \(\mathrm{k}\) members was formed from the \(\mathrm{n}\) members of a certain company's board of directors. Each member of the committee sent exactly one email summarizing his or her perspective on the committee's findings to each board member who was not a member of the committee, and to no one else. The total number of these email summaries sent was \(\mathrm{35}\).
Select values for k and for n that are jointly consistent with the given information. Make only two selections, one in each column.
4
5
6
10
12
Let's create a simple diagram to understand the email flow:
Board of Directors (n members total)
┌─────────────────────────────────────┐
│ Committee (k) │ Non-Committee │
│ │ (n - k) │
│ ● ● ● ... ● │ ○ ○ ○ ... ○ │
│ k members │ (n-k) members │
└─────────────────────────────────────┘
↓
Each ● sends one email to each ○
Total emails = k × (n - k) = 35
Each committee member sends emails to (n - k) non-committee members.
With k committee members, total emails = \(\mathrm{k} \times (\mathrm{n} - \mathrm{k}) = 35\)
We need values of k and n from the given choices that satisfy:
Let's test each possible value of k:
If k = 4:
\(4(\mathrm{n} - 4) = 35\)
\(4\mathrm{n} - 16 = 35\)
\(4\mathrm{n} = 51\)
\(\mathrm{n} = 12.75\) (not an integer, so invalid)
If k = 5:
\(5(\mathrm{n} - 5) = 35\)
\(5\mathrm{n} - 25 = 35\)
\(5\mathrm{n} = 60\)
\(\mathrm{n} = 12\) ✓
Verification: \(5 \times (12 - 5) = 5 \times 7 = 35\) ✓
? Stop here - we found our answer.
The committee has 5 members from a board of 12 members. Each of the 5 committee members sends one email to each of the 7 non-committee members, totaling \(5 \times 7 = 35\) emails.