I have a circular necklace with #18# beads on it. All the beads are different. Making two cuts with a pair of scissors, I can divide the necklace into two strings of beads. If I want each string to have at least #6# beads, how many differe?
...how many different pairs of strings can I make?
...how many different pairs of strings can I make?
1 Answer
Jun 17, 2018
Explanation:
If we have 18 beads altogether, and after cutting no string has less than 6 beads, then we can choose from 6 at a time to 12 at a time:
We can only choose up to 12 at a time, since the remaining string must have at least 6 beads.
So we want the number of combinations of: