Exercise · ZW-COMBINATIONS-WITH-REPETITION-005 · ★☆☆ Basic
6 objects are chosen from 4 types, with repetition and without order. How many selections are there?
Choose one option.
Show answer
- B. 84
Explanation
There are \(\binom{4+6-1}{6}=\binom{9}{6}=84\). The value 15 is \(\binom{6}{4}\) and 4096 is \(4^6\), which counts with order.
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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