20. What is the area of a piece of metal foil that measures 43.9 cm by 29.21 cm? Express the answer to
the correct number of significant figures.
a. 128 cm2
b. 1280 cm?
1280.3 cm?
d. 1280.32 cm
128.0319 cm?
C.
e.

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.