求PREP-PS-1-36 思路

jesuisdesole

36.   4841-!-item-!-187;#058&004235

In a certain deck of cards, each card has a positive integer written on it.  In a multiplication game, a child draws a card and multiplies the integer on the card by the next larger integer.  If each possible product is between 15 and 200, then the least and greatest integers on the cards could be

 

(A) 3 and 15

(B) 3 and 20

(C) 4 and 13

(D) 4 and 14

(E) 5 and 14

ANS: C

望辰莫及

有人知道么。。。

望辰莫及

貌似明白了，between15 ,200不代表要取到15和200两个值。。。=。=

uustar

一组整数，最小n的乘以（n+1）和最大的m乘以(m+1)在15到200之间，问n和m。

即n(n+1)>15和m(m+1)<200，n>=4，m<=13