F.5 probability >URGENT!!!!!< 15 points!!!

2008-08-25 7:58 am
唔該你地列d steps出黎啊?? 千萬唔好一步過, thanks!!!!!!
一定要有解釋啊唔該{其實我有晒d steps答案但係我睇唔明~~}


1. John throws a die twice, find the probability that the numbers on the die
are the same. ((我寫6/36x6/36<<因為兩次嘛 但係又唔岩!!?? why?))

2. A fair die is tossed 2 times. What is the probability that the results are in
the order "2" and "4"?

3. In a lucky draw, there are 6 different colours of balls in the bag, the one
who can get the "black" ball can get the first prize. If Mr Chan is the third
to pick the ball in the bag, find the probability that he can get the first prize.
((佢又唔講有冇replacement..咁到底係當佢有定冇???))

4. There are 3 red balls and 3 white balls in box A and 2 red balls and 4 white
balls in box B. Draw a ball from box A and put it into box B. Find the
probability the ball from box B is "red".
((我想問佢講第二句黎做咩呢??))

5. Two students A and B play 2 games of table tennis. A's chance of winning
a game is 3/5. Find the probability that each of them wins one game?
((佢又唔講B贏/敗的probability點計啊?? 同埋2/5係咪A會輸的
probability???))

6. For a biased die, the experimental probabilities of the numbers are found to
be: P(1)=1/3, P(2)=2/9 and P(3)=P(4)=P(5)=P(6). The die is thrown twice.
Find the probability of getting two "6"s.
((咁P(3)的probability係咪1/9? then我完全唔識計...))

7. There are 5 members A, B, C, D, E in the round table to attend the monthly
meeting. The order of the seats is randomly arranged. Find the probability
that A sits next to B.
((完全唔識點做~~~~))


**thanks 要有解釋<<<一定一定!!!
**就算你地淨係識一題兩題都要答呀唔該!!!!!!因為好urgent!!!!!!!!!!!
更新1:

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回答 (2)

2008-08-25 7:19 pm
✔ 最佳答案
All question except no. 2 and 7 are answered by water_610610, thus, I will
answer question 2 and 7.

2. A fair die is tossed 2 times. What is the probability that the results are in
the order "2" and "4"?

Answer:

Total no. of possible results: 6*6= 36
No. of result that is in the order of "2" and "4"= 1

Therefore, (P)= 1/36
-----------------------------------------------------------------------------------------

7. There are 5 members A, B, C, D, E in the round table to attend the monthly
meeting. The order of the seats is randomly arranged. Find the probability
that A sits next to B.

Answer:
Assume B's seat is fixed.

Then, no. of seats which A can sit= 5-1= 4
No. of seats that is next to B= 2 (The left and the right side of B)

Therefore,
(P)= 2/4= 1/2
-----------------------------------------------------------------------------------------

2008-08-29 21:50:08 補充:
1. John throws a die twice, find the probability that the numbers on the die
are the same.

Answer:
No. of possible results when two dices are drawn: 6*6= 36
No. of results that the numbers on the dices are the same: 6
Therefore,
P(Numbers are the same)= 6/36= 1/6

2008-08-29 21:50:23 補充:
2. A fair die is tossed 2 times. What is the probability that the results are in
the order "2" and "4"?

Answer:

Total no. of possible results: 6*6= 36
No. of result that is in the order of "2" and "4"= 1

Therefore, P(Order of "2" and "4")= 1/36

2008-08-29 21:50:54 補充:
3. Answer:
* I believe the lucky draw should have replacement.

The possibility that the black ball is not picked by the first person: 5/6
The possibility that the black ball is not picked by the first person: 5/6
Therefore,

P(Mr Chan got the first prize): 5/6*5/6*1/6= 25/ 216

2008-08-29 21:51:39 補充:
4. Answer:
* The second sentence states that box B now has one more ball, which is picked from Box A.

Possibility that a red ball is picked from box A to B: 3/6= 1/2
Possibility that a white ball is picked from box A to B: 3/6= 1/2

2008-08-29 21:52:15 補充:
4. Answer(continue):
Possibility that a red ball is picked up from box B after a red ball is transferred from box A to B= 1/2* 3/7= 3/14

2008-08-29 21:52:27 補充:
4. Answer(continue):
Possibility that a red ball is picked up from box B after a white ball is transferred from box A to B= 1/2* 2/7= 2/14
Therefore,

P(a red ball is picked up from box B)= 3/14+ 2/14= 5/14

2008-08-29 21:52:47 補充:
5. Answer:
Possibility that A wins a game= 3/5
Possibility that A loses a game (ie. B wins the game)= 1-3/5= 2/5
Therefore,

P(Each of them wins one game)= 2/5*3/5= 6/25

2008-08-29 21:53:01 補充:
6. Answer:
Possibility of getting a “6” in a throw: (1-(1/3+2-9))/4= 1/9
Therefore,

P(getting two “6”s)= 1/9*1/9= 1/81

2008-08-29 21:53:16 補充:
7. Answer:
Assume B's seat is fixed.

Then, no. of seats which A can sit= 5-1= 4
No. of seats that is next to B= 2 (The left and the right side of B)

Therefore,
P(A sits next to B)= 2/4= 1/2

2008-08-29 21:54:23 補充:
Here are the solutions for all the questions, hope it helps.
參考: Me. Hope it helps., Me. Hope it helps.
2008-08-25 8:29 am
1.要same,即可以係1,1 2,2 3,3 4,4 5,5 6,6 第1次係1的prob.係1/6 第2次係1都係1/6 ,所以係1/6 x1/6 , 但同no.的出現有6個可能 所以1/6x1/6x6

2./

3.((佢又唔講有冇replacement..咁到底係當佢有定冇???))<--我諗個情況係要拎prize,,應該都要公平咁抽,,,應該係有replacement的
prob.= 5/6 x 5/6 x 1/6

4.Draw a ball from box A and put it into box B <- 即係e+ b 會多左個ball 由6變7 原本有3紅3白係a, 2紅4白係b , 如果由a抽個ball去b係白色(prob.= 3/6),咁再係b抽的ball要係紅色就變左2/7 , 如果係a去b的係紅,b抽的係紅就變左3/7 所以 prob. = 3/6x2/7 + 3/6 3/7

5. a win的prob.係3/5 即佢2/5會lose,,,a一lose就即係b會win,即b的win prob.係2/5 , lose prob.係3/5 所以prob.係(a win)x(b lose)+ (a lose)x(b win) = 3/5x3/5 + 2/5x2/5

6. p(6)= 1 - (1/3 + 2/9) = 4/9 , 有1,2的prob. 1- p1 -p2 = p3,4,5,6
prob.= 4/9x4/9

7. 唔識



唔太sure- -~
參考: 自己


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