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  1. Jiyad Ahsan

    Mathematics: Post your doubts here!

    part 3, sorry it took so much time oh and i forgot to mention ( though its obvious) the denominators cancel out a part of the numerators so only the 8P8 's are left
  2. Jiyad Ahsan

    Mathematics: Post your doubts here!

    part (i) 12P8 =19958400 part (ii) so frances and mary do not sit together, just find out the number of ways in which they DO sit together and subtract from the total if they sit together then 11P7 x 2P2 - - - - (11P7 because since they sit together you count them as one unit, 2P2 because they...
  3. Jiyad Ahsan

    Mathematics: Post your doubts here!

    okay part (ii) since there are 4 groups each with 3 possessions so you have 3! x 3! x 3! x 3! (or 3!^4 do that the 3 possessions can be arranges within their group) multiplied by 4! (so the 4 groups can be arranged as well) 3!^4 x 4! =31104
  4. Jiyad Ahsan

    Mathematics: Post your doubts here!

    thanx alot man ! :)
  5. Jiyad Ahsan

    Mathematics: Post your doubts here!

    okay so if order doesnt matter its 3876 and since 4 are selected you multiply by 4! =93024 another way to explain it is that nCr = n! / r! (n-r)! - - - and nPr = n!/ (n-r)! so if you cancel it out nPr = nCr x r! and i'm solving b(ii) right now,will post it in a bit
  6. Jiyad Ahsan

    Mathematics: Post your doubts here!

    Alice123 question number please
  7. Jiyad Ahsan

    Mathematics: Post your doubts here!

    Ryan123 can you explain this please
  8. Jiyad Ahsan

    Mathematics: Post your doubts here!

    awesome ! i didnt even remember that formula :p Zenia ZZ the solution you were looking for. Q5 from november 11 / paper 61
  9. Jiyad Ahsan

    Mathematics: Post your doubts here!

    yeah i know alice i read the table as well and the value in the ms is on 0.97 while the in the question its given quite clearly '94%' probably the value in the ms is wrong... maybe :p
  10. Jiyad Ahsan

    Mathematics: Post your doubts here!

    listen man, if in binomial distribution the value of np and nq exceeds 5 you have to use normal approximation if it says less than ( < ) you minus 0.5 from the x greater than ( > ) you add o.5 to x if its less than or equals to ( ≤ ) you add 0.5 if its greater than or equals to ( ≥ ) you minus...
  11. Jiyad Ahsan

    Mathematics: Post your doubts here!

    lol i meant just that, but i missed it out thnx for pointing it out :) though i think you can use just one 8 or 32
  12. Jiyad Ahsan

    Mathematics: Post your doubts here!

    that satement is in Q5 they say that 94% is within 12g of the mean (which is 20g) which means that if you take 20+12 = 32 (which is 12 g away form the mean) or 20-12=8 the probability of (8<x<32) is 94% (94/100 = 0.94) so the mean would be 20, x would be 8 or 32 and the probability will be o.94
  13. Jiyad Ahsan

    Mathematics: Post your doubts here!

    the mean is always (Σ(x-a)/n ) + a, 133/n + 25 = 28.325 since assumed mean,a is given 25 and Σ(x-a) is given 133 and mean is given 28.325 so we find n=40, then just use the s.d formula that i gave before and u'll have variance = 82.99 and s.d = 9.11 for part (ii) the normal formula for...
  14. Jiyad Ahsan

    Mathematics: Post your doubts here!

    (i) okay umm in the first part you found that n was 10 by solving o.75^n < 0.06 (ii) since mean is np (n is the nymber of trials and p is the probability of success) you get the mean which is 10.5 (by 14 x o.75) we find the mean because the question said that the two nearest values to that...
  15. Jiyad Ahsan

    Mathematics: Post your doubts here!

    oh umm right i'll edit it in the original post as well they give you two things right? the and the so you have to do Σ(x-a)^2 _ ( Σ(x-a) )^2 just put the two numbers they give you in the question in formula (obviously the Σ(x-a)^2 given would be larger...
  16. Jiyad Ahsan

    Mathematics: Post your doubts here!

    by the way if someone could please explain (hopefully before our paper :p) why and when (in what conditions) in normal distribution do we subtract from 1, from what i've learned till now.. Φ(-a) = 1 - Φ(a) here to remove the negative sign P(Z > a) = 1 - Φ(a) here (apparently) to remove the...
  17. Jiyad Ahsan

    Mathematics: Post your doubts here!

    P(X < 34.6) P (Z < 34.6-41.1/3.4 ) P (Z < -1.912) =Φ (-1.912) =1 - Φ (1.912) as Φ(-a) = 1 - Φ(a) =1-0.9713 =0.0287 =0.028 multiply that by 0.95 =0.95 x 0.028 =0.0266 (reasons and explanation below) since its given that the probability that 5th symphony rhyme is...
  18. Jiyad Ahsan

    Mathematics: Post your doubts here!

    we all have those 'brain not working' days, kher ogae :p
  19. Jiyad Ahsan

    Mathematics: Post your doubts here!

    (2C2 x 9C4) + (2C0 x 9C6) = 186 + 84 = 210 total 11 questions right? you have two conditions, either both questions or none well say first you choose both the questions so you'd have 2C2 multiplied by the rest 4 questions will be chosen from the 9 remaining so 9C4 the other condition if 2C0...
  20. Jiyad Ahsan

    Mathematics: Post your doubts here!

    umm ok this is a method known as assumed mean, you basically take a number and assume that it is the mean of a set of numbers (lets say we have 16, 17, 19, 21, 22) so I 'assume' the mean is 20 and the i calculate the difference of every number from that assumed mean. first lets just do it. then...
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