The marks on an examination are normally distributed with a mean of 72% and a standard deviation of 8.1%. The top 20% of students are accepted into this college. To the nearest percent, what is the minimum mark the college will accept for entrance?
How do I do this standard deviation/statistics question?
You have to use z-scores. Using a z-score chart, find the z-score which will represent the lower 0.80 of the normal curve, leaving 0.2 (the top 20%).
z-score = (needed score - mean score)/standard deviation
Plug in and simplify.
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