9.82 The weights of aluminum grains follow a lognormal distribution, which means that the natural logarithms of the grain weights follow a normal distribution. A sample of 177 aluminum grains has logweights averaging 3.04 with a standard deviation of 0.25. (The original weight measurements were in 10–4 gram.) Estimate the true mean logweight of the grains from which this sample was selected, using a confidence coefficient of 0.90. (Source: Department of Materials Science, University of Florida.)