The photographs below show how a change in climate is affecting the size of Grinnell Glacier in Glacier National Park. Which of the following best explains the change in the glacier between 1910 and 1997? A. Higher average temperatures
B. Higher frequency of earthquakes
C. Higher total precipitation
D. Higher rates of wind erosion

The chemical composition of soil varies with depth. an article in communications in soil science and plant analysis describes chemical analyses of soil taken from a farm in western australia. fifty specimens were each taken at depths 50 and 250 cm. at a depth of 50 cm, the average no3 concentration (in mg/l) was 88.5 with a standard deviation of 49.4. at a depth of 250 cm, the average concentration was 110.6 with a standard deviation of 51.5. find a 95% confidence interval for the difference in no3 concentrations at the two depths.