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习题练习:Counting Principles 

 作者: admin发布日期: 2024-06-02 22:24   总分: 16分  得分: _____________

答题人: 游客未登录  开始时间: 24年06月02日 22:24  切换到: 整卷模式

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1#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Find the number of ways in which twelve different baesakv()0 r vt/5y;tgdbiv 2:m4a*qpk seball cards can be given to Emily, Harr eg(: 0iv5v t/rdap4kab;v*ytq k2ms) y, John and Olivia, if Emily is to receive 5 cards, Harry is to receive 3 cards, John is to receive 3 cards and Olivia is to receive 1 card.   

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2#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Tyler needs to decide the order in whic;d : buy;:bh)frs4i1-nrglhw* nd m8rh to schedule 11 exams for his school. Two of these exams are Chemistry ( 1 SL and 1 HL). Find the number of different ways Tyler can schedule the 11 exams given that the two Chemistry su1lu*srn4;b:f:rnb -;him r8 )d dhwyg bjects must not be consecutive.$\approx a \times 10^{b}$ a =    b =   

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3#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A school basketball team of 5 students is s-r h mr u;oq+h0is(/ hloib+)zelected from 8 boys and 4 girls.
1. Determine how many possible teams can be chosen.   
2. Determine how many teams can be formed consisting of 3 boys and 2 girls?   
3. Determine how many teams can be formed consisting of at most 3 girls?   

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4#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A police department has 4 male and 7 femal)5 (c nnmy5ua -rsy3jge officers. A special group of 5 officers is to be amu 3yyr 5(cn5gas-)j nssembled for an undercover operation.
1. Determine how many possible groups can be chosen.   
2. Determine how many groups can be formed consisting of 2 males and 3 females.   
3. Determine how many groups can be formed consisting of at least one male.   

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5#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In an art museum, there are 8 different paintrjirhe1 v-eqpadd (-z.m0 a)3e;z 2t uings by Picasso, 5 different paintings by Van Gogh, and 3 different paintings by Rembrandt. The curator of the museum wants to hold an exhibition in a hall that can only display a maximum of 7 paintings at a tiz)0 hdid3pra 1vq;mtjeu --a(z2re. eme.
The curator wants to include at least two paintings from each artist in the exhibition.
1. Given that 7 paintings will be displayed, determine how many ways they can be selected.   
2. Find the probability that more Rembrandt paintings will be selected than Picasso paintings or Van Gogh paintings.   

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6#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Peter needs to decide the order in which 7 3mr9lx(uns tto schedule 14 exams for his school. Two of these exams areu3n9 ts(lr m7x Chemistry ( 1 SL and 1 HL). Find the number of different ways Peter can schedule the 14 exams given that the two Chemistry subjects must not be consecutive.$\approx a \times 10^{b}$ a =    b =   

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7#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Ten students are to be arranf bo4z;gmdrql/;6 cp:j k14dz ged in a new chemistry lab. The chemistry lab is set out in two rows of f;qf pdocz dkj;/z44:m6 1rgblive desks as shown in the following diagram.



1. Find the number of ways the ten students may be arranged in the lab.

Two of the students, Hugo and Leo, were noticed to talk to each other during previous lab sessions.   
2. Find the number of ways the students may be arranged if Hugo and Leo must sit so that one is directly behind the other. For example, Dest 1 and Desk 6 .   
3. Find the number of ways the students may be arranged if Hugo and Leo must not sit next to each other in the same row.   

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8#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
An arts and crafts store is offering da3 c3moa z,o h1/ fceb8p7zv t:aqht70qb+a.a special package on personalized keychains. Customers can choose to personalize their keychains with up to 3 different charms from a selectionb/fmqa 7d7baph,ot.31t8 zech +ov :ca3a0z q of 6 different types of charms.
Determine how many ways a customer can personalize a keychain if
1. The order is important.
2. The order is not important.
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9#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A professor and five of his stu-7er dmw y uyw r9e-cong-z:50h6v4ewdents attend a talk given in a lecture series. They have a row of 8 seae- eww- v6ry0oywde m4: h7-9g cnu5rzts to themselves.
Find the number of ways the professor and his students can sit if
1. the professor and his students sit together.   
2. the students decide to sit at least one seat apart from their professor.   

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10#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Julie works at a book store and has nine books to diox4zpsam 2- 3usplay on the main shelf of the store. Four of the books are non-fiction and five are fiction. Each book is different. Determine the number of possible ways Julie can line up the nine books on the ax 34zsum- op2main shelf, given that
1. the non-fiction books should stand together;   
2. the non-fiction books should stand together on either end;   
3. the non-fiction books should stand together and do not stand on either end.   

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11#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Sophia and Zoe compete in v -c2war)jj7oien qcd7 i9 /2:tdrir 6a freestyle swimming race where there are no tied finishes and there is a total of 10 competitors. Find the total number of possible ways in which the ten swimmers can finish if Zoej)q-/nidjc:ti ew767 2r2oi dv 9arc r finishes
1. in the position immediately after Sophia;   
2. in any position after Sophia.   

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12#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  There are 11 players on a football team who ai dbz+ar.edee04 fg(3re asked to line up in one straight line for a team photo. Three of the team members named Adam, Brad and Chris refuse to stand next to each other. There is no restriction on the order in which thd4f zeigbre+ 0 .(d3aee other team members position themselves.
Find the number of different orders in which the 11 team members can be positioned for the photo.   

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13#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  There are six office cubicles arranged in a grid with two rows andkz3:c)pd w8 +r4n qhnq three columns as shown in the following diagram. Aria, Bella, Charlotte, Danna, and Emma are to be stationed inside the qp4k3q+z dn:w8crh ) ncubicles to work on various company projects.
Find the number of ways of placing the team members in the cubicles in each of the following cases.
1. Each cubicle is large enough to contain the five team members, but Danna and Emma must not be placed in the same cubicle.   
2. Each cubicle may only contain one team member. But Aria and Bella must not be placed in cubicles which share a boundary, as they tend to get distracted by each other.   

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14#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The barcode strings of a new product are created from feiyif7g) (qq* o,o.wx our letters $ \mathrm{A}$, $\mathrm{B}$, $\mathrm{C}$, $\mathrm{D}$ and ten digits $0,1,2, \ldots, 9$ . No three of the letters may be written consecutively in a barcode string. There is no restriction on the order in which the numbers can be written. Find the number of different barcode strings that can be created.$\approx a \times 10^{b}$ a =    b =   

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15#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Sophie and Ella play a gjzh,b iwrm389z nds;(dzk-5s 5wya*h ame. They each have five cards showing roman numerals I, V, X, L, C. Sophie lays hernwzsdhzs,yam8 bk(r 3 59hdzij;5*- w cards face up on the table in order I, V, X, L, C as shown in the following diagram.


Ella shuffles her cards and lays them face down on the table. She then turns them over one by one to see if her card matches with Sophie's 4 card directly above. Sophie wins if no matches occur; otherwise Ella wins.
1. Show that the probability that Sophie wins the game is $\frac{11}{30}$ .

Sophie and Ella repeat their game so that they play a total of 90 times. Let the discrete random variable X represent the number of times Sophie wins.   
2. Determine:
1. the mean of X ;   
2. the variance of X .   

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16#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Jack and John have decided to play a game. They will be rollingbdt- 8 fo()ub4 1tx86q gxhewm a die seven times. One roll of a die is considered as one round of the game. On each round, John agrees to pay Jack 4 dollars if 1 or 2 is rolled, Jack agrees to pay John 2 fx )t4do w1bu8t g6eqx8hb(-mdollars if 3,4,5 or 6 is rolled, and who is paid wins the round. In the end, who earns money wins the game.
1. Show that the probability that Jack wins exactly two rounds is $\frac{224}{729}$ .
2. 1. Explain why the total number of outcomes for the results of the seven rounds is 128 .
2. Expand $(1+y)^{7}$ and choose a suitable value of y to prove that

$128=\binom{7}{0}+\binom{7}{1}+\binom{7}{2}+\binom{7}{3}+\binom{7}{4}+\binom{7}{5}+\binom{7}{6}+\binom{7}{7}$ .

3. Give a meaning of the equality above in the context of the seven rounds.
3. 1. Find the expected amount of money earned by each player in the game.
2. Who is expected to win the game?
3. Is this game fair? Justify your answer.
4. Jack and John have decided to play the game again.
1. Find an expression for the probability that John wins five rounds on the first game and two rounds on the second game. Give your answer in the form

$\binom{7}{r}^{2}\left[\frac{1}{3}\right]^{s}\left[\frac{2}{3}\right]^{t}$

where the values of r, s and t are to be found.
2. Use your answer to (d) (i) and seven similar expressions to write down the probability that John wins a total of seven rounds over two games as the sum of eight probabilities.
3. Hence prove that

$\binom{14}{7}=\sum_{k=0}^{7}\binom{7}{k}^{2}$

5. Now Jack and John roll a die 12 times. Let A denote the number of rounds Jack wins. The expected value of A can be written as

$\mathrm{E}[A]=\sum_{r=0}^{12} r\binom{12}{r}\left[\frac{a^{12-r}}{b^{12}}\right]$

1. Find the value of a and b .
2. Differentiate the expansion of $(1+y)^{12}$ to prove that the expected number of rolls Jack wins is 4 .

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