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Thread: Hi, please help me this one Statistic question for test tomorrow?

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    Hi, please help me this one Statistic question for test tomorrow?




    1. Subway Sandwiches wishes to introduce a new condiment, carrot, to its sandwiches. To test whether "carrots" will be well-received by its customers, two samples, one with customers aged between 18 dan 30 and another sample with customers aged between 31 and 50 were taken. A total of 50 customers were surveyed per group.

    The proportion of customers aged between 18 and 30 who liked the new condiment was 45% while 35% of those in the higher age group didn't like the condiment. Test at the 10% significance level whether there is a difference in the proportions of young and older customers who liked the new condiment.

    2. A normal population has mean of 45 and standard deviation of 3. You Select a sample of 40. Compute the probability of sample mean is:

    a) Less than 44
    b) Between 44 and 46
    c) Greater than 46

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    Re: Hi, please help me this one Statistic question for test tomorrow?


    This is actually 2 Statistics questions...

    2) Because a normal distribution is symmetric, percentage less than 44 will be equal to percentage greater than 46. So the answer to a = the answer to c. Then the answer to b will be (1 - (a+c))

    \mu = 45 \sigma = 3 Sample Size = 40

    Standard error = \frac{\sigma}{\sqrt{Sample\ Size}}= \frac{3}{\sqrt{40}} = .474

    Use the standard error to calculate the z-score

    z-score = \frac{44 - 45}{.474} = -2.11

    Then you look up -2.11 in the Normal table to get .0174 or 1.74%

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