
không siu cứ ăn gian ...Bây giờ em có 3 bài toán nè , nhờ 2 chị vận dụng trí thông minh giải giùm :
1- There are 10 socks of each of the following colors in a drawer: blue, green, red, yellow & white, for a total of 50 socks. If the socks are randomly distributed in the drawer (i.e. not in pairs or any other grouping), & you are blindfolded, what is the minimum number socks you must draw from the drawer in order to be certain you have at least 2 socks of the same color?
Answer: 6
2- If you are in the same situation as in the preceding problem, how many socks must you draw from the drawer in order to be certain you have at least 2 socks of different colors?
Answer: 11
3- If there are 4 empty seats in a movie theatre, how many permutations are there for the number of ways 4 people could sit in these seats?
Answer: 24. The answer can be found by starting with 4 numbers or letters, such as 1234, & counting upward using only these 4 numbers to find all of the possible permutations: 1234, 1243, 1324, 1342, etc.