July sales for Melodic Kortholt. Limited, average μ1 = $8,800 with σ1² = $1,260. August sales average μ2 = $7,900 with σ2² = $1,350. September sales average μ3 = $8,000 with σ3² = $1,580. Find the mean and standard deviation of total sales for the third quarter. (Round your standard deviation to 4 decimal places.)