Posted by rebecca on .
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.
Z-score = (X-μ)/σ
Look up normal distribution tables to find P(Z≥1)=0.8413
So 15.87% of students have better scores than 75%.