77. The article Orchard Floor Management Utilizing Soil-Applied Coal Dust for Frost Protection (Agric.

Forest Meteorology, 1988: 71—82) reports the following values for soil heat ux of eight plots covered with coal dust.

34.7 35.4 34.7 37.7 32.5 28.0 18.4 24.9 The mean soil heat ux for plots covered only with grass is 29.0. Assuming that the heat- ux distribution is approximately normal, does the data suggest that the coal dust is effective in increasing the mean heat ux over that for grass? Test the appropriate hypotheses using a  .05.