Answer:
16.7% of GMAT scores are 647 or higher
Step-by-step explanation:
The Empirical Rule states that 68% of the values are within 1 standard deviation of the mean(34% above, 34% below). It also considers that 50% of the values are above the mean and 50% are below the mean.
In this problem, we have that the mean is 547 and that the standard deviation
is 100.
a. What percentage of GMAT scores are 647 or higher?
647 is 1 standard deviation above the mean.
So, 50% of the values are below the mean. Those scores are lower than 647.
Also, there is the 34% of the values that are above the mean and are lower than 647.
So, there is a 50% + 34% = 84% percentage of GMAT scores that are 647 or lower.
The sum of the probabilities must be 100
So, the percentage of GMAT scores that are 647 or higher is 100% - 84% = 16%.