How many different combinations of pennies,nickels,dimes,quarters,and dollars can a piggy bank contain if it has 20 coins in it?

分类: 作业答案 • 2022-02-19 21:48:18

问题描述：

How many different combinations of pennies,nickels,dimes,quarters,
and dollars can a piggy bank contain if it has 20 coins in it?

答

即是问a+b+c+d+e=20有多少组正整数解.
用隔板法,在一列二十个1之间插入四个隔板,情况有C(19,4)=3876种情况