An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to make an estimate at th

Question

An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to make an estimate at the 85% level of confidence. For a sample of 295 third graders, the mean words per minute read was 26.9. Assume a population standard deviation of 2.7. Construct the confidence interval for the mean number of words a third grader can read per minute. Round your answers to one decimal place

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Thanh Thu 4 years 2021-08-15T11:12:47+00:00 1 Answers 16 views 0

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  1. lethu
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    2021-08-15T11:14:13+00:00
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    Answer:

    85% level of the confidence interval is

    (26.337, 26.662)

    Step-by-step explanation:

    Explanation:-

    Given the size of the sample ‘n’ = 295

    Mean of the sample x⁻ = 26.5

    The Standard deviation of the Population = 2.7

    85% level of the confidence interval is determined by

    (x^{-} - Z_{0.15} \frac{S.D}{\sqrt{n} } , x^{-} + Z_{0.15} \frac{S.D}{\sqrt{n} })

    Critical value Z₀.₁₅ = 1.036

    85% level of the confidence interval is determined by

    (x^{-} - Z_{0.15} \frac{S.D}{\sqrt{n} } , x^{-} + Z_{0.15} \frac{S.D}{\sqrt{n} })

    (26.9 -1.036 \frac{2.7}{\sqrt{295} } , 26.5 + 1.036 \frac{2.7}{\sqrt{295} })

    ( 26.5 – 0.1628 , 26.5+0.1628)

    (26.3372,26.6628)

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