Empirically we can see the σ ranges of a Gaussian distribution in the following figure
From exercise we know that:

We will calculate how many sigmas the given range is to know what the percentage of scores :

The score 131.3 is 2 sigmas from the mean

The score 168.9 is 2 sigmas from the mean
The range of reasoning scores between 131.3 and 168.9 is ±2σ which corresponds to 95.5% (see initial graph)