In a large Biology class the scores of the final exam were a

In a large Biology class, the scores of the final exam were approximately normally distributed with mean 80.5 and standard deviation 9.9. What proportion of final exam scores were greater than 78.5?

Write only a number as your answer. Round to 4 decimal places (for example 0.0048). Do not write as a percentage.

Solution

P(X>78.5) = P((X-mean)/s >(78.5-80.5)/9.9)

=P(Z>-0.20) = 0.5793 (from standard normal table)