The internal audit staff of a local manufacturing company performs a sample audit each quarter to estimate the proportion of accounts that are more than 90 days overdue (delinquent). The company's quarterly audit reports indicate that 18 percent of accounts have been delinquent on average over the past 8 years. For this quarter, the audit staff randomly selected 250 customer accounts and found that 48 were overdue (delinquent). Find the mean of the sampling distribution of the sample proportion. Use Excel to find probabilities and values. Round final answer to four decimals