Statistics

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In a distribution of 400 response times with a mean of 7 minutes and a standard deviation of 2 minutes, the maximum number of response times greater than 13 minutes would be about:

A. 40
B. 100
C. 75
D. 90

  • Statistics -

    According to
    http://davidmlane.com/hyperstat/z_table.html

    the probability of a time greater than 13 minutes is .00135

    None of your choices result from that probability.

  • Statistics -

    Z = (x - μ)/SD

    Z = (13-7)/2 = 6/2 = 3

    Look up this Z in a table in the back of your statistics text covering areas under the normal distribution for the smallest area. Multiply this value by 400.

    Unfortunately, that does not fit any of your choices. Do you have any typos?

  • Statistics -

    No. No typos. That's how its written on the packet I am doing. Thank You so much for your help though, I guess my teacher might've made a typo...

  • Statistics -

    The result of an exam score for a given class is normally distributed. If the mean score is
    85 points and the standard deviation is equal to 20 points, find the cutoff passing grade
    such that 83.4% of those taking the test will pass

  • Statistics -

    The manager of a hotel has stated that the mean guest bill for a weekend is Birr 400 or
    less. A member of the hotel’s accounting staff has noticed that the total charges for guest
    bills have been increasing in recent months. The accountant will use a sample of weekend
    guest bills to test the manager’s claim.
    Required: State the null and alternative hypotheses

  • Statistics -

    A manager wishes to find out whether there is a relationship between the number of radio
    advertisement aired per week and the amount of sales (in hundreds of Birr) of a product.
    The data for the sample are given below.
    Number of Advertisement (X) 2 5 8 8 10 12
    Sales (Y) 2 4 7 6 9 10
    Compute the value of the correlation coefficient and explain the degree of relationship

  • Correlation cofficient and degree of relationship -

    A manager wishes to find out whether there is a relationship between the number of radio
    advertisement aired per week and the amount of sales (in hundreds of Birr) of a product.
    The data for the sample are given below.
    Number of Advertisement (X) 2 5 8 8 10 12
    Sales (Y) 2 4 7 6 9 10
    Compute the value of the correlation coefficient and explain the degree of relationship

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