The owner of a local golf course wants to estimate the difference between the average ages of males and females that play on the golf course. He randomly samples 20 men and 21 women that play on his course. He finds the average age of the men to be 35.022 with a standard deviation of 8.119. The average age of the women was 31.298 with a standard deviation of 7.975. If a 90% confidence interval is calculated to estimate the difference between the two average ages, what is the margin of error? Assume both population standard deviations are equal.