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  1. A

    Simple Probability Question

    I thought so too.
  2. A

    Simple Probability Question

    But the question did not say at least one person passed, it said only one person passed. This means that S,G passing but E failing is not a desirable outcome. Are you sure this doesn't effect the answer? Is the textbook answer incorrect?
  3. A

    Simple Probability Question

    The answer in the back of the book is \frac{5}{17}. Isn't the sample space, or the number of possible outcomes reduced when one person, and only one, must pass? Question 16c, 10C Cambridge 3U HSC for reference.
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    Simple Probability Question

    I struggle with this topic, though I'm trying to get better. I'd appreciate it if you could show me the working for this question: $Sophia, Gabriel and Elizabeth take their driving test. The chances they pass are $\frac{1}{2}$, $\frac{5}{8}$, and $\frac{3}{4}$ respectively. If only one of them...
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    Prelim Polynomials Question

    I am 90% sure this question is wrong, but I wanted to post it here just in case I'm wrong. $Show that a polynomial with leading term $-x^3$ and a double root at $x=1$ has another root at point where $x>1. This is from Margaret Grove's Preliminary Maths in Focus 3 Unit textbook - 12.5 Q20. I...
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    HSC 2015 MX1 Marathon (archive)

    Re: HSC 2015 3U Marathon It's not the site's fault, it's codecogs'.
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    bionomials help

    $The expansion of $(x+y)^4$ is $1x^4y^0+4x^3y^1+6x^2y^2+4x^1y^3+1x^0y^4\\$Therefore, the middle term is: $6x^2y^2\\$Now we sub in our x and y, which are $2x$ and $-4$ respectively.$\\6\times(2x)^2(-4)^2=384x^2
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    Three Permutations and Combinations Questions

    Lucky I bought that one after yesterday!
  9. A

    Prelim 2015 Chit Chat Thread

    Just did my 3U paper today. It was much harder than any other past paper I had ever done.
  10. A

    Cambridge Prelim MX1 Textbook Marathon/Q&A

    Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread I don't think you've missed any solutions.
  11. A

    Three Permutations and Combinations Questions

    Yeah, I've learnt that rule. This makes sense now.
  12. A

    Three Permutations and Combinations Questions

    I am so fucking done with this textbook.
  13. A

    Three Permutations and Combinations Questions

    Why wouldn't the first part be (n-k+1)! ? The number of "things" being arranged is n-k (the amount of people not in the group) and one more, the group itself. For example, if you have a 5 people with 3 of those people in a group, you have the two people not in the group, and the group itself...
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    Three Permutations and Combinations Questions

    You're going to love this... MIF. The only reason I'm using it is because Cambridge doesn't seem to have a P&C section.
  15. A

    Three Permutations and Combinations Questions

    Are you sure? The textbook says 126.
  16. A

    Three Permutations and Combinations Questions

    Would you please explain your reasoning for this?
  17. A

    Three Permutations and Combinations Questions

    Sorry, the answer to the third question is given as 126 in the textbook.
  18. A

    Three Permutations and Combinations Questions

    That seems logical, the quantity of numbers about 30 000 should be less than the total quantity of numbers. I believe it should be \frac{3\times4!}{2!}, which is equal to 36, the same as your calculation. The textbook definitely give 72 as the correct answer, however, at this stage I guess it's...
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    Three Permutations and Combinations Questions

    Hey everyone, please explain how to do these... 1. Numbers are formed from the digits 1, 2, 3, 3, and 7 at random. In how many ways can they be arranged to form a number greater than 30 000? (Answer is 72). My thinking: In that question, I understand that the first number must be a 3, 3...
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    Prelim 2015 Chit Chat Thread

    Make a new thread, people wont notice it here.
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