Mathematics: Post your doubts here!

[Mad-Eye]

Eight cards are selected with replacement from a standard pack of playing cards
with 12 pic cards, 20 odd cards
and 20even cards.
a) how many different sequences of cards are possible?
b) how many of the sequencees in part (a) will contain three picture cards, three odd cars and two even cards??

 

[ppaayas]

FIRST FIND THE PROBABILITY THAT RAJ's score is 12 with both even and odd numbers on the spinner.
Probability of getting an even number on the spinner is 2/5 and then of getting 12 is P(2,6)*2 + P(3,4)*2
So it becomes 2/5 *( P(2,6)*2 + P(3,4)*2)=2/45
now for the odd one. Probability of getting an odd number on the spinner is 3/5 but this time u will have to add two numbers to get 12 and hence p(6,6)=3/5*1/6*1/6=1/60
so P(SCORE=12) is 1/60 +2/45 =11/180
To find the conditional probability P(E|12) =2/45 devided by 11/180 = 8/11

But where do you get the six from? Its five-sided?

 

[hassam]

umm i think because 2 G"s can be placed before the 7 letters or after them..

dint undrstnd......it has nth to wid dat

 

[smartangel]

http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_w11_qp_61.pdf
Q3i..how d owe get the probability table? as in i dont knw how to get the probabilites..i dont understand ms method..

 

[smartangel]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_61.pdf
Q6..a ii.. why dont we do 4! x 8! x 6 /2! x 2! x 3!
4! for the vowels..8! for the rest and 6 because the vowels(that we consider as 1 group of 4) can occupy any place right?

 

[smartangel]

GUYS. come on. some help would be highly appreciated. i"ve posted so many queries..plz answer..paper tomorrow!!

 

[mukki]

But where do you get the six from? Its five-sided?

dude the spinner is 5 sided not the two dice

 

[mukki]

But where do you get the six from? Its five-sided?

totally forgot to tell you that dude the score must be calculated from the dice

 

[ppaayas]

Thank you helpful guy! What grade are you prospecting?

 

[mukki]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_61.pdf
Q3i..how d owe get the probability table? as in i dont knw how to get the probabilites..i dont understand ms method..

x 1 2 3 4 because there are 4 people to be selected and x represents the number of girls selected.
P(X=1) = p(bbbg)*4!/3!=3/8 * 2/7 *1/6 * 5/5 * 4= 1/14
P(X=2) =p(bbgg) *4!/(2!*2!) = 3/8 * 2/7 * 5/6 * 4/5 *6 = 3/7
P(X=3) =p(bggg) *4!/3! = 3/8 * 5/7 *4/6*3/5 *4 = 3/7
P(X=4) =p(gggg) *4!/4! = 5/8 * 4/7 * 3/6 * 2/5 = 1/14
You have to make arrangements here to because any guy/girl can be selected first .Here you go just remember after a girl/guy is selected he/she cant be selected again so consider without replacement

 

[mukki]

Thank you helpful guy! What grade are you prospecting?

dont know dude depends on the paper and if my brain is functioning at that time too many thoughts you know

 

[mukki]

I keep getting 7.61 :S
and question 4(ii) i found the LQ and UQ and got that right but i dont get how they got the 5 and 20 :/ sorry

just use more than 3 s.f for the mean which u take while calculating the standard deviation it gives a more precise answer

 

[sunnyexo]

Can anyone help me with this question...It's about permutation= =2011 OCT statistic 9709/62-------Q2
http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_w11_qp_62.pdf

 

[Wanzi21]

Can u explain this??

 

[Khan_971]

Q.6 part 2:
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_62.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_ms_62.pdf
Why they do 1 - 0.214??

im gonna do this paper now and will try to get back to you.

 

[Khan_971]

www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_62.pdf
Q.5 part 2:
why do they multiply the probablities by 3! ??
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_ms_62.pdf
explain pls...

There are 3 different objects which can be put in any order. hence 3!

 

[mukki]

I dont get it..

can u please explain it in more simpler terms?
i dont get wht u assumed x1 and x2 to be and what 2fi(z)-1=0.34 means?

dude the mean time for standard journey is between two time right ? thats y they are saying to ask the least and greatest values for the time. after standardizing ul make it P(-z<Z<z)

 

[smartangel]

http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_s11_qp_61.pdf
Q3..plz tell me how do we calculate other values of probabilitty of x?

 

[mominzahid]

dude the mean time for standard journey is between two time right ? thats y they are saying to ask the least and greatest values for the time. after standardizing ul make it P(-z<Z<z)

I still dont get it.. :S
ok forget that question im too dumb to understand it lol..:/
can u please explain this how we find the standard deviation?

 

[Khan_971]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_63.pdf
Q2 and 3..explain plz

Q2. You should draw a tree diagram for this. Then you will understand. See, the questions if you analyze asks for everything except Males NOT watching the kids. Hence add up all probabilities except Males watching. it is 5/6. if you try to answer numerically, it usually doesnt come right.

Q3. A factory is making 3m to 5m ropes in the ratio 4:1.
part i) now you can draw a table in which 1st row is labelled 3m and 5m. 2nd row the probability of that 1 rope being 3 or 5m.

Lengths .........3m.....5m
Prob. ....... 4/5..... 1/5
And u know how to find E(x) and Var from this table.

Part ii) they can be 3,5 or 5,3 since 2 ropes of different lengths. Hence, (4/5 x 1/5) x 2 (since 2 arrangements)

part iii) the only possibility is a combination of 3+3+5. it can be 5,3,3 or 3,5,3. Therefore, (4/5 * 4/5 * 1/5) * 3!/2! (since 3 objects but 2 are the same)