Final answer:
The approximate standard deviation of the shoe prices in the department store is 20.
Step-by-step explanation:
To find the approximate standard deviation of the shoe prices in the department store, we need to use the given information that d is greater than 20 for approximately 32% of the pairs of shoes.
Since d represents the distance of the price of each pair of shoes from the mean price of $74, we can say that d is a measure of how much the price of a pair of shoes deviates from the mean price.
Based on the given information, we can assume that d represents the standard deviation of the shoe prices. Therefore, the approximate standard deviation of the shoe prices is 20.