在做蓝书（上）时，碰到的几个不理解的问题

chongov

142页66题
A family made a down payment of $75 and borrowed the balance on a set of encyclopedias that cost $400. The balance with interest was paid in 23 monthly payments of $16 each and a final payment of $9. The amount of interest paid was what percent of the amount borrowed?
正确答案是16%，但我算出来是13%（没有一个选项是这个答案）

143页73题
Square RSTU shown above is rotated in a plane about its center in a clockwise direction the minimum number of degrees necessary for T to be in the position where S is now shown. The number of degrees through which RSTU is rotated is____
正确答案是270°。我看不懂红色的那两段

147页91题
In each production lot for a certain toy, 25 percent of the toys are red and 75 percent of the toys are blue. Half the toys are size A and half are size B. If 10 out of a lot of 100 toys are red and size A, how many of the toys are blue and size B?
正确答案是35，我算出来是30。按题目所说的意思，红色型号A的玩具，其数量应该是蓝色型号B的玩具的3倍才对。

147页93题
What is the least possible product of 4 different integers, each of which has a value between -5 and 10, inclusive?
正确答案-3600，我算出的是-5040。因为按题意所算出的最小乘积便是-5×10×9×8＝-3600，而题中问的是“最不可能”的答案。

lauchen

1.（23×16+9）/（400-75）=1.16
2. clockwise direction 是指“顺时针”， 第二部分是指，T点跑到S点需要转动的度数
3.  red size A 10个， red Size B 则为 15个（因为red一共25个）， 　blue size B 就是 50 -15=35 （ size B 一共50）
4. least 在这里是指最小， 10×9×8× （-5）

chongov

down payment 是在400元中减去的部分吗？

lauchen

是的，类似买房子的首付款

chongov

知道了，谢谢