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At an election, a voter may vote for any...

At an election, a voter may vote for any number of candidates not greater than the number to be chosen. There are 7 candidates and 4 members are to be chosen. In how many ways can a person vote ?

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To solve the problem of how many ways a person can vote for candidates in an election where there are 7 candidates and 4 members to be chosen, we can break it down step by step. ### Step-by-Step Solution: 1. **Understanding the Problem**: - We have 7 candidates. - We need to choose up to 4 members. - A voter can choose any number of candidates from 0 to 4. 2. **Choosing Candidates**: - The possible choices for the number of candidates a voter can select are: - Choosing 0 candidates (not voting at all) - Choosing 1 candidate - Choosing 2 candidates - Choosing 3 candidates - Choosing 4 candidates 3. **Using Combinations**: - The number of ways to choose \( r \) candidates from \( n \) candidates is given by the combination formula \( \binom{n}{r} \). - Therefore, we need to calculate: - \( \binom{7}{0} \) for choosing 0 candidates - \( \binom{7}{1} \) for choosing 1 candidate - \( \binom{7}{2} \) for choosing 2 candidates - \( \binom{7}{3} \) for choosing 3 candidates - \( \binom{7}{4} \) for choosing 4 candidates 4. **Calculating Each Combination**: - \( \binom{7}{0} = 1 \) (There is 1 way to choose no candidates) - \( \binom{7}{1} = 7 \) (There are 7 ways to choose 1 candidate) - \( \binom{7}{2} = \frac{7 \times 6}{2 \times 1} = 21 \) (There are 21 ways to choose 2 candidates) - \( \binom{7}{3} = \frac{7 \times 6 \times 5}{3 \times 2 \times 1} = 35 \) (There are 35 ways to choose 3 candidates) - \( \binom{7}{4} = \frac{7 \times 6 \times 5 \times 4}{4 \times 3 \times 2 \times 1} = 35 \) (There are 35 ways to choose 4 candidates) 5. **Summing All the Combinations**: - Now, we add all the combinations together: \[ \text{Total ways} = \binom{7}{0} + \binom{7}{1} + \binom{7}{2} + \binom{7}{3} + \binom{7}{4} \] \[ = 1 + 7 + 21 + 35 + 35 = 99 \] ### Final Answer: Thus, the total number of ways a person can vote is **99**.
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