In a sample of 70 stores a certain company, 58 violated a scanner accuracy standard. It has been demonstrated that the conditions for a valid large sample confidence interval for the true proportion of the stores that violate the standard were not met. Determine the number of stores that must be sampled in order to estimate the true proportion to within 0.05 with 95% confidence using the large-sample method.
What is the number of stores that must be sampled?