提問三道數(shù)學(xué)題
1.S is a set of n consecutive integers.比較the mean of S與the median of S大小 答案是一樣大
我知道Mean=(a1+an)/2,當(dāng)n=2k時(shí),median=(ak+ak+1)/2；當(dāng)n=2k+1時(shí),median=ak+1,問題是怎么比較出mean和median想等的?（n,k,k+1均為a的角標(biāo)）
2.If 9 trees are originally planted in a
circular pattern(就是9個(gè)點(diǎn)圍成一個(gè)圓圈),what is the least number of trees that
must be transplanted so that the 9 trees will be in 2 straight rows?
咋做?答案是9-2*2=5,這是啥意思?（此題的圖無法上傳,若實(shí)在不明題意,就不必回答）
3.A rectangular rug covers half of a
rectangular floor that is 9 feet wide and 12 feet long.If the dimensions of the
rug are in the same ratio as those of the floor,how many feet long is the rug?答案是6根號(hào)下2
請(qǐng)問既然rug蓋住floor一半,為何不能認(rèn)為其長(zhǎng)或?qū)捠莊loor的一半?而是非要通過面積一半來算?