Statistic

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Final averages are typically approximately normally distributed with a mean of 78 and a standard deviation of 11. Your professor says that the top 6% of the class will receive an A; the next 24%, a B; the next 41%, a C; the next 18%, a D; and the bottom 11%, an F. (Give your answers correct to one decimal place.)

(a) What average must you exceed to obtain an A?

(b) What average must you exceed to receive a grade of C or better?

(c) What average must you obtain to pass the course? (You'll need a D or better.)

You may need to use the appropriate table in Appendix B to answer this question.

  • Statistic -

    Z = (score-mean)/SD

    Find table in the back of your statistics text labeled something like "areas under normal distribution" (That should be Appendix B.) to find the proportions and their Z scores. Insert values in above equation and calculate for the scores.

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