A camp director is interested in the mean number of letters each child sends during his/her camp session. The population standard deviation is known to be 2.5. A survey of 20 campers is taken. The mean from the sample is 7.9 with a sample standard deviation of 2.8. Construct a 90% confidence interval X : Which distribution should you use for this problem? State the confidence interval. Round to 2 decimal places. Calculate the error bound. Round to 2 decimal places Which of the following is the correct set of answers? O X =7.9 0 = 2.5 n = 19 Student t Distribution (6.98, 8.82) 0.92 O X =7.9 0 = 2.8 n = 20 Student t Distribution (7.0, 8.8) 0.90 O X =7.9 0 = 2.5 n = 20 Normal Distribution (6.98, 8.82) 0.92 O X = 7.9 0 = 2.8 7 = 20 Normal Distribution (7.0, 8.8) 0.90