Noise levels at various area urban hospitals were measured in decibels. The mean of the noise levels in 24 randomly selected corridors was 61.8 decibels. The sample standard deviation is 6.9. Find the 90% confidence interval of the true mean. Assume the distribution of noise level is normal.

2. using calculations based on a perpetual inventory system, determine the inventory balance altira would report in its august 31, 2021, balance sheet and the cost of goods sold it would report in its august 2021 income statement using the average cost method. (round "average cost per unit" to 2 decimal places.)