Question

（滿分12分）為了防控甲型H1N1流感，某校積極進行校園環(huán)境消毒，購買了甲、乙兩種消毒液共100瓶，其中甲種6元/瓶，乙種9元/瓶．

1.（1）如果購買這兩種消毒液共用780元，求甲、乙兩種消毒液各購買多少瓶？

2.（2）該校準備再次購買這兩種消毒液（不包括已購買的100瓶），使乙種瓶數(shù)是甲種瓶數(shù)的2倍，且所需費用不多于1200元（不包括780元），求甲種消毒液最多能再購買多少瓶？

 

Answer 1

【答案】

 

1.（1）解法一：設(shè)甲種消毒液購買瓶，則乙種消毒液購買瓶．··················· 1分

依題意，得．

解得：．············································································································ 3分

（瓶）．················································································ 4分

答：甲種消毒液購買40瓶，乙種消毒液購買60瓶．····················································· 5分

解法二：設(shè)甲種消毒液購買瓶，乙種消毒液購買瓶．·············································· 1分

依題意，得·························································································· 3分

解得：············································································································· 4分

答：甲種消毒液購買40瓶，乙種消毒液購買60瓶．

2.（2）設(shè)再次購買甲種消毒液瓶，剛購買乙種消毒液瓶．··································· 6分

依題意，得．················································································· 8分

解得：．··········································································································· 9分

答：甲種消毒液最多再購買50瓶．

【解析】略