有兩個在2到90之間（包含2與90）的整數，主持人請甲和乙兩個數字邏輯分析高手猜這兩個數。先同時告知甲乙雙方：兩個數的和大於11、兩數的積小於260。再單獨告訴甲這兩個數的和，單獨告訴乙這兩個數的積。由甲乙輪流發言，請甲先說。
第一步，甲：我不知道這兩個數，但我知道乙也不知道這兩個數。
第二步，乙:一開始我不知道之兩個數，但知道甲也不知道這兩個數：現在我仍然不知道是哪兩個數。（乙還有一句話：「無法判斷甲現在是否知道是哪兩個數」沒有說出來。）
第三步，甲：我仍然不知道是哪兩個數。
第四步，乙：哈哈！我知道是哪兩個數了!
第五步，甲：哈哈，我也知道這兩個數了！
請問：這是哪兩個數?
有一個牢房，有3個犯人關在其中。因為玻璃很厚，所以3個人只能互相看見，不能聽到對方說話的聲音。」
有一天，國王想了一個辦法，給他們每個人頭上都戴了一頂帽子，只叫他們知道帽子的顏色不是白的就是黑的，不叫他們知道自己所戴帽子的是什麼顏色的。在這種情況下，國王宣布兩條如下：
1．誰能看到其他兩個犯人戴的都是白帽子，就可以釋放誰；
2．誰知道自己戴的是黑帽子，就釋放誰。
其實，國王給他們戴的都是黑帽子。他們因為被綁，看不見自己罷了。於是他們3個人互相盯著不說話。可是不久，心眼靈的A用推理的方法，認定自己戴的是黑帽子。您想，他是怎樣推斷的?
【專題 GMAT邏輯題】
Maize contains the vitaminniacin, but not in a form the body can absorb. Pellagra is a disease thatresults from niacin deficiency. When maize was introduced into southern Europefrom the America in the eighteenth century, it quickly became a dietary staple,and many Europeans who came to subsist primarily on maize developed pellagra.Pellagra was virtually unknown at that time in Americas, however, even among peoplewho subsisted primarily on maize.
Whichof the following, if true, most helps to explain the contrasting incidence ofpellagra described above?
(A)Once introduced into southern Europe, maize became popular with landownersbecause of its high yields relative to other cereal crops.
(B)Maize grown in the Americas contained more niacin than maize grown in Europedid.
(C)Traditional ways of preparing maize in the Americas convert maize』s niacin intoa nutritionally useful form.
(D)In southern Europe many of the people who consumed maize also ate niacin-richfoods.
(E) Before the discovery of pellagra』slink with niacin, it was widely believed that the disease was an infection thatcould be transmitted from person to person.
