Answer:
16% of GMAT scores are 647 or higher.
Explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the z-score of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
The average GMAT score is 547 (Magoosh website). Assume that GMAT scores are bell-shaped with a standard deviation of 100.
This means that

What percentage of GMAT scores are 647 or higher?
The proportion is 1 subtracted by the p-value of Z when X = 647. So



has a p-value of 0.84.
1 - 0.84 = 0.16
0.16*100% = 16%
16% of GMAT scores are 647 or higher.