Turn on thread page Beta
    • Thread Starter

    Well I got bored so i typed out my answers...

    1. X ~ Po(8) Probability = 0.184

    2. i think it was E(X-Y) = 12 - 7 = 5
    Var(X-Y) = Var(X) + (-1^2)Var(Y) = 11.5
    E(3X+2Y) = 3E(X) + 2E(Y) = 50
    Var(3X+2Y) = 9Var(X) + 4Var(Y) = 91

    Need independence = Var(X-Y) and Var(3x + 2Y)

    3. i) xbar = 9.1
    ii) Reason 1: xbar of second test isn't the same as xbar of first test
    Reason 2: the upper value of the interval for the second test is not in the range of the 90% confidence interval (it should be...)

    iii) n=70

    4. chi squared question? most of it was prove stuff. my value in the largest cell was 4.0 something i think. .'. conclude more men teach in higher education than women

    5. very long chi squared question (9marks) Worked out the expected values using Binomial distribution. Then combined rows 3-6 so that E > 5.

    Final value was X^2 = 10.8 or 11.8 ish i think

    chi squared with 3 dof was 7.779 i think if it was the 0.10 sig level. Hence reject H0, binomial is not a good model for the data.

    6. i) f(x) = 2/pi 0 < x < pi/2 (0 otherwise)

    ii) F(x) = 2x/pi 0< x < pi/2 (0 for x<0 and 1 for x>pi/2)

    iii) X = sin^-1(y/300)

    iv) F(Y) = (2/pi)sin^-1(y/300) for 0 < y < 300

    v) p( boat more than 100m away) = 1 - [(2/pi)sin^-1(100/300)] = 0.784

    7. I can't remember the values at all for this one.

    i) The CI was [ -0.10 , 2.4 ish]

    ii) use two sample t test. i think t = 1.998 which was greater than critical value so reject H0, there is evidence that the second sample have lost more weight (mewx < mewy)

    iii) assume equal variance. This is fair as the ppl will be from similar populations/both wanting to lose weight (i kinda blabbled through this one)
    • Thread Starter

    There was also a 1 mark part to question 5 i don't remember. I think it asked for an assumption but maybe not?

    Yes! I got your answers (I can't remember the rest). By the way, that question was something like "Is it fair to assume all the students had been guessing their answers?"

    The answer was no, since the test statistic was far too large.

    Edit: I put a different reason two. I said that the confidence interval for the second one should have been larger than the first, since a larger z value would have been used for a greater % confidence value, hence a larger interval.
    • Thread Starter

    ah yeh i got it the wrong way round lol.

University open days

  • Staffordshire University
    Everything except: Midwifery, Operating Department Practice, Paramedic Undergraduate
    Sun, 21 Oct '18
  • University of Exeter
    Undergraduate Open Days - Exeter Campus Undergraduate
    Wed, 24 Oct '18
  • University of Bradford
    Faculty of Health Studies Postgraduate
    Wed, 24 Oct '18
Who is most responsible for your success at university

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.