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Thread: help with hypotheses testing (wait time for random 25 customers)

  1. #1
    New Member
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    Nov 2017
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    help with hypotheses testing (wait time for random 25 customers)

    So i've recently started brushing up on some areas of maths i'm not farmiliar with and have come across hypotheses testing. Up to this point a friend was helping me out but she's now away until the new year so here i am.

    Here's the first of three questions she left me with:
    1. A hypothesis test is to be performed to determine whether the mean waiting time during peak hours for bus customers has increased, due to congestion and/or some other factor, from the previous mean waiting time of 8.2 minutes.

    Previous experience indicates that the waiting time follows a normal distribution with a standard deviation of 3.8 minutes. To test the hypothesis, a random sample of 25 customers will be selected. This sample of 25 customers yields a mean of 9.75 minutes


    1. State appropriate null and alternative hypotheses using the standard formal mathematical notation
    2. Write down what type of test this is. (two-tailed test, left-tailed test....)
    3. Assuming a significance level of 0.05, whats the critical/rejection region for this test?

    dont know why i just cant seem to get on with this topic, if anyone can point me to a good write up/video covering this i'd really appreaciate it.

    So far i think my data is:

    n = 25
    = 8.2
    x̅ = 9.75
    σ = 3.8

    first part: (cringe)
    Ho : σ = 3.8 Ha : σ < 3.8

    Also is H1 the same as Ha for the alternate? seen both used in different places.


    thanks in advance for any help or guidance.

    Jimmy.
    Last edited by Jimm; 11-27-2017 at 11:39 AM.

  2. #2
    Elite Member
    Join Date
    Apr 2005
    Location
    USA
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    8,907
    Pretty good start. Take a closer read on the problem statement. It asks about the mean waiting time. You defined your hypotheses in terms of the standard deviation, not the mean. Give that another go.
    "Unique Answers Don't Care How You Find Them." - Many may have said it, but I hear it most from me.

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