Given: n = 48, the sample size m = $25,000, th sample mean σ = $3000, the maximum variance
The standard deviation is s = √σ = √(3000) = 54.772
As a rule of thumb, the range is 4 times the standard deviation. Therefore the range is R = 4*54.772 = 219.09 Half the range is R/2 = 219.09/2 = 109.45
The required range is (25000-109.45, 25000+109.45) = (24890.46, 25109.54)