Exercise · ZW-COMBINATIONS-WITH-REPETITION-002 · ★☆☆ Basic

3 donuts are chosen from 5 available types, with repetition and without order. How many selections are there?

Choose one option.

Show answer
  • D. 35

Explanation

There are \(\binom{5+3-1}{3}=\binom{7}{3}=35\). The 10 is \(\binom{5}{3}\), which does not allow repetition.

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Review the concept: Combinations with repetition

A combination with repetition of size \(k\) from \(n\) types of object is an unordered selection of \(k\) objects in which each type may be chosen several times.

\[\binom{n+k-1}{k}\]

More practice problems: combinations with repetition

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