There seems to be no end to how large the signing bonuses professional athletes can obtain when they start their careers (Peyton Manning - $11.6 million). Suppose a sample of 18 new NFL players report their signing bonuses at the start of the 1998 season, and the results show a mean of $3.81 million and a standard deviation of $1.7 million. Estimate with 90% confidence the mean signing bonus for that season (in millions).