The easiest way to determine the score is to use a calculator or spreadsheet and the appropriate probability function.
If you want the top 10%, the score corresponds to the 90th percentile. That score is 316.
If you want the top 15%, the score corresponds to the 85th percentile. That score is 313.
X/26=28
•26=•26 (cancels each other out)
X=728
The answer would be c. it is a flat Sudanese so you only need to square it