$(30$ pts$)$ Exploration boreholes for a tabular lignite deposit have been drilled as shown below. The

deposit is roughly $20$ ft thick, and varies in thermal value. Sample values from each hole are given in

BTU$/$lb$.$ The density of compacted lignite is $60l\frac{b}{f}{t}^3.$

a$.$ Using the "INCLUDED AREA" method, construct blocks for reserve estimation.

b$.$ Determine the area of each block $(f{t}^2).$

c$.$ Determine the weighted average heat value of each block $($BTU$/$lb$).$

d$.$ Estimate the total lignite reserves $($tons$)$ and total heat value of the reserves $($BTU$).$

e$.$ Repeat steps a$-$d using the "AREA OF INFLUENCE" method and report your new estimate for

total lignite reserves and heat value. Comment on the change in your reserve estimate $($i$.$e$.,$

how and why did the estimate change?$)$