A random sample of 20 houses selected from a city showed that the mean size of these houses is 1880 square feet with a standard deviation of

Question

A random sample of 20 houses selected from a city showed that the mean size of these houses is 1880 square feet with a standard deviation of 320 square feet. Assume that the sizes of all houses in this city have an approximate normal distribution. The upper bound the 90% confidence interval for the mean size of all houses in this city is: A. 2110 B. 1941 C. 1974 D. 1968 E. 1894

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Arianna 2 weeks 2021-09-11T02:27:47+00:00 1 Answer 0

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    2021-09-11T02:29:19+00:00

    Answer:

    Option C

    Step-by-step explanation:

    Given that for a  random sample of 20 houses selected from a city showed that the mean size of these houses is 1880 square feet with a standard deviation of 320 square feet.

    X, the sizes of houses is Normal

    Hence sample mean will be normal with

    Mean = 1880

    and std dev = \frac{320}{\sqrt{20} } \\=71.5542

    For 90% confidence interval critical value for t with degree of freedom 19 is

    1.328

    Confidence interval upper bound

    = mean + margin of error

    = 1880+1.328*71.55\\=1975

    Option C is right

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