statistics

A class test resulted in a mean score of 60% and a standard deviation of 15%. You scored 75%. Assuming the scores follow a normal distribution, and there are 200 in the class, how many students scored better than you? Give your answer to the nearest whole number.

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1. Z-score = (X-μ)/σ
=(75-60)/15
=1

Look up normal distribution tables to find P(Z≥1)=0.8413

So 15.87% of students have better scores than 75%.

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