From the given data it is clear that the total sales in the first month in the midwest are 428. We get this figure if we add 362 current stores and 66 new stores.
Now, if we calculate what percentage of sales are current stores sales in the midwest in the first month's sale, we get:
%
Which is approximately what the model had predicted (the model had predicted 85%).
Similarly, if we calculate what percentage of stores are new stores sales in the midwest in the first month's sale, we get:
%
Again, this result is very close to the model which predicted the percentage of new stores sales in the Midwest to be 15%.
Thus, we see that the above data is largely consistent with the sales director’s model.