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題組五

題組五. 小健撲滿中有 1 元、 5 元、 10 元硬幣,共 1400 元,清點結果發現 5 元硬幣個數是 10 元硬幣個數的 3 倍、 1 元硬幣個數是 5 元硬幣個數的 15 倍,請問: 1.10 元硬幣有多少個? 2. 撲滿中有多少個硬幣?. 重點分析. 一、假設硬幣數目最少的為 X 個 二、尋找數學等式. ( 因此: 10 元硬幣個數 X 個, 5 元硬幣個數就有 3X 個, 1 元硬幣個數就有 15*3X 個 ). ( 1 元、 5 元、 10 元硬幣總和共有 1400 元 ). 下一步. 承上題.

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題組五

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  1. 題組五 小健撲滿中有1元、5元、10元硬幣,共1400元,清點結果發現5元硬幣個數是10元硬幣個數的3倍、1元硬幣個數是5元硬幣個數的15倍,請問: 1.10元硬幣有多少個? 2.撲滿中有多少個硬幣? 重點分析 一、假設硬幣數目最少的為X個 二、尋找數學等式 (因此:10元硬幣個數X個, 5元硬幣個數就有3X個, 1元硬幣個數就有15*3X個) (1元、5元、10元硬幣總和共有1400元) 下一步

  2. 承上題 小健撲滿中有1元、5元、10元硬幣,共1400元,清點結果發現5元硬幣個數是10元硬幣個數的3倍、1元硬幣個數是5元硬幣個數的15倍,請問: 1.10元硬幣有多少個? 2.撲滿中有多少個硬幣? 設10元硬幣有X個,共有10*X元 5元硬幣為10元硬幣的3倍即3X個, 共有5*3X元 1元硬幣是5元硬幣的15倍即45X個,共有1*45X元 重點分析 10*X + 5*3X + 1*45X=1400 所以 10X+15X+45X=1400 70X=1400 X=20 故10元硬幣有20個,共有200元 5元硬幣為10元硬幣的3倍即60個, 共有300元 1元硬幣是5元硬幣的15倍即900個,共有900元 撲滿中有980個硬幣

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