【尚友制造】[GMAT数学]数学概率大专题

标题：[GMAT数学]数学概率大专题尚友论坛【GMAT专区】【尚友学堂GMAT公开课】【GMAT机经专区】【GMAT资料下载区】【GMAT黄历查询】以前讲GMAT数学课的时候，讲的专题。

那么以后每天更新一题吧1. In how many ways can 9 people be seated in a row of chairs if two of the people, David and Becky,refuse to sit together?2. A fair coin is tossed 10 times. What is the probability that two heads do not occur consecutively?3. Cain prepared 4 different letters to be sent to 4 different addresses. For each letter, he preparedan envelope with its correct address. If the 4 letters are to be put into the 4 envelopes at random, 1) what is the probability that only 1 letter will be put into the envelop with its correct dress? 2)that no letter will be put into the envelope with its correct address? 3)that all letters will be put into theenvelope with its correct ad dress?4. There are y different travelers who each have a choice of vacationing at one of N differentdestinations. What is the probability that all y travelers will end up vacationing at the samedestination?5. A small company employs 3 men and 5 women. If a team of 4 employees is to be randomlyselected to organize the company retreat, what is the probability that the team will have exactly 2 women?6. A certain basket contains 10 apples, 3 of which are green and 7 of them are red. If three different apples are selected at random from the basket, what is the probability that 2 of them are red and 1 of them is green?7. A certain telephone number has seven digits. If the telephone number has the digit zero exactly 3 times, and the number 1 is not used at all, what is the probability that the phone number contains one or more prime digits.8. Anthony and Michael sit on the six member board of directors for company X. If the board is to be split up into 2 three-person sub committees, what percent of all the possible subcommittees that include Michael also include Anthony?9. Two couples and one single person are seated at random in a row of five chairs. What is the probability that neither of the couples sits together in adjacent chairs?10. A committee of three people is chosen from five married couples. What is the number of different committees that can be chosen if two people who are married to each other cannot both serve on the committee?11. From a group of 3 boys and 3 girls, 4 children are to be randomly selected. What is the probability that equal numbers of boys and girls will be selected?12. A box contains 10 pairs of shoes (20 shoes in total). If two shoes are selected at random, what it is the probability that they are matching shoes?13. Kate and Danny each have $10. Together, they flip a fair coin 5 times. Every time the coin lands on heads, Kate gives Danny $1. Every time the coin lands on tails, Danny gives Kate $1. After the five coin flips, what is the probability that Kate has more than $10 but less than $15?14. A bag contains 3 red, 4 black and 2 white balls. What is the probability of drawing a red and a white ball in two successive draws, each ball being put back after it is drawn?15. A fair coin with sides marked heads and tails is to be tossed eight times. What is the probability that the coin will land tails side up more than five times?16. A box contains 3 yellow balls and 5 black balls. One by one, every ball is selected at random without replacement. What is the probability that the fourth ball selected is black?17. The oasis output of Abu Ilan in the heart of the Negev desert, has a population of 20 Bedouin tribesmen and 20 Farma tribesmen. El Kamin, a nearby oasis, has a population of 32 Bedouin tribesmen and 8 Farima tribesmen. A lost soldier (from another country), accidentally seperated from his army unit, is wandering through the desert and arrives at the edge of one of the oases. The soldier has no idea which oasis he has found, but the first person he spots from a distance is a Bedouin. What is the probability that he wandered into Abu Illan? What is the probability that he is in El Kamin?18. A man can hit a target once in 4 shots. If he fires 4 shots in succession, what is the probabilitythat he will hit target19. In his pocket, a boy has 3 red marbles, 4 blue marbles, and 4 green marbles. How many will hehave to take out of his pocket to ensure that he has taken out at least one of each color?20.a jar contains only x black balls and white balls. One ball is drawn randomly from the jar and is notreplaced. A second ball is then drawm randomly from the jar. What is the probability that the first ball drawn is black and the second ball drawn is white?21.4对夫妇，从中任意选出3人组成一个小组，不能从任一对夫妇中同时选择两人。