?4??72k 45k1≈5.07，k2≈?5.07（舍去） ························································································· 6分
∴CD?5.07?2≈10.14（m） ···························································································· 7分 又设最多可安装n扇窗户
∴1.5n?0.8(n?1)≤10.14 ··································································································· 9分
n≤4.06．
答：最多可安装4扇窗户． ································································································· 10分 （本题不要求学生画出4个表示窗户的小矩形）