prep中两个数学题，急

１．whenever Martin has a restaurant bill with ann amount between $10 and $99, he calculates the dollar amount od the tip as 2times the tens digit of the amount of the bill. if the amount of Martin's most recent bill was between $10 and $99, was the tip calculated by Martin on the bill greater than 15 percent of the bill?

(1) the amount of the bill was between $15 and $50

(2) the tip calculated by Martin was $8

答案是B．可是总的amount不知道啊？即使是between $10 and $99，可以＞１５％，也可以＜１５％．

高人来说说

２．Rectangular solid是指正多面体？是否和Regular solid/polyhedron 一个意思？正多面体是各个面都全等吗？

还DS题：求Rectangular solid的表面积

（１）一个面的面积是４８

（２）一个棱长为３

答案好象是E．如果正多面体是各个面都全等，那(1)为什么错？

第二題的rectangular是長方形喔

所以只有1是不行的...

8/49是>0.15的啊．希望高人继续解答

那Rectangular solid指的是长方体么？

那也应该是选C吧？？ls不是两个条件都用上了么？

是的  solid就是固體的意思

所以rectangular solid 就是長方體

只要能判断是否就可以是正确答案，并非一定要说是，或者一定要说否，8/49>0.15, 8/40>0.15足以说明可以通过B知道～