4. A marketing research firm surveyed 49 randomly selected residents in North Texas to determine the mean amount spent on coffee during 1 week. The sample mean was $20 per week. The population...

4. A marketing research firm surveyed 49 randomly selected residents in North Texas to determine the mean amount spent on coffee during 1 week. The sample mean was $20 per week. The population distribution in normal with a standard deviation of $5.

Using the 95% level of confidence, determine the confidence interval for μ.

Lower Boundary (your answer should be in the format $xx.xx)