In a marketing campaign, a company utilizes machine learning algorithms to predict customer behavior based on historical data. The algorithm analyzes various features such as age, purchase history, and engagement metrics. If the model predicts that a customer is likely to make a purchase with a probability of 0.75, what is the expected number of purchases from a sample of 200 customers? Additionally, if the company wants to achieve a 90% confidence interval for the expected number of purchases, what would be the appropriate margin of error if the standard deviation of the predicted purchases is estimated to be 5?