Answer:
In a normal distribution the 68% of the total sample is within the mean + or - the deviation, in this case the 68% (238 pages) of the sample will have between 40 and 24 images per page.
It also means that the share of the sample with the probability to have more than 56 pictures(mean+3 deviations) or less than 8 pictures (mean-3deviations) is only of 0.3%, given that the normal distribution include the 99.7% within the values of mean +/- 3 deviations.
Explanation: