AMC 8 2002 Problem 2
AMC8 2002 年第 2 题
特殊数与不定方程★★☆☆☆
How many different combinations of $5 bills and $2 bills can be used to make a total of $17? Order does not matter in this problem.
有多少种方法可以将若干 5 元纸币和 2 元纸币组成总额为 17 元？这道题里不考虑顺序。
- A.2
- B.3
- C.4
- D.5
- E.6
正确答案 · Correct Answer
A
解析 · Solution
Solution 1
https:
You cannot use more than 4 <dollar>5 bills, but if you use 3 <dollar>5 bills, you can add another <dollar>2 bill to make a combination. You cannot use 2 <dollar>5 bills since you have an odd number of dollars that need to be paid with <dollar>2 bills. You can also use 1 <dollar>5 bill and 6 <dollar>2 bills to make another combination. There are no other possibilities, as making <dollar>17 with 0 <dollar>5 bills is impossible, so the answer is 2.
继续练习