Remember that the line inside the box represents the median of the data set; thus, 50 percent of the data set is to the left, and the remaining part of the data set is to the right of that line.
On the other hand, the right side of the box represents the upper quartile and marks 75% of the data.
Thus, between the upper quartile and the median, we can find 75%-50%=25% of the data.
Therefore, since the data set consists of 68 scores, the answer is
The answer is 17 scores