0

Can you help me to find out the solution of this problem and explain the answer?

1 Answers1

1

$\binom{21+6-1}{6} = $230230 Or $\binom{21+6-1}{20} = $230230

Using starts and bars method: For 21 varieties we need 20 bars for selecting the items. Then, we will have (20+6) or (21+6-1) choices '6' stars or (donuts) and '20' to separate the different kinds of donuts (as in the Q: Varieties) as shown below:

_ _ _ _ _ _ _ _ _  _ _  _  _  _  _  _  _  _  _  _  _  _  _  _  _  _
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Or: |**|*|** ..... *|*


And from these options we can either select the 6 donuts "Starts" or, the 20 "Bars" which we use to separate between tests.