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S1: Z-score (sample error/central limit theorem) Watch

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    I don't understand how you do these questions. Please teach me how.

    I know how to read z-scores from the table BTW.

    Question:
    In term time, the average total weekly times spent on schoolwork by maths teachers in England are distributed with mean 42.4 hours and standard deviation 5.2 hours.

    b) Find the limits within the central 95% of such sample means should lie.

    c) How large a sample would be needed in order that the central 95% of the sample means would lie in an interval of 2.5 hours?

    Thanks, please teach me how I do these questions! Thank you so much.
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    Nevermind, figured it out.............
 
 
 
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