You rent a car for $29.85. the first 140 miles are free, but each mile thereafter costs $0.12. you plan to drive it 165 miles. what is the marginal cost of driving the car? a- the marginal cost is whatever can be purchased with $29.85 plus $16.56. b- the marginal cost is $29.85. c- the marginal cost is $3.00 plus the cost of gas. d- the marginal cost is the cost of gas plus the initial payment plus some additional payment.

Farmers know that driving heavy equipment on wet soil compresses the soil and injures future crops. here are data on the "penetrability" of the same type of soil at two levels of compression. penetrability is a measure of how much resistance plant roots will meet when they try to grow through the soil. compressed soil 2.85 2.66 3 2.82 2.76 2.81 2.78 3.08 2.94 2.86 3.08 2.82 2.78 2.98 3.00 2.78 2.96 2.90 3.18 3.16 intermediate soil 3.17 3.37 3.1 3.40 3.38 3.14 3.18 3.26 2.96 3.02 3.54 3.36 3.18 3.12 3.86 2.92 3.46 3.44 3.62 4.26 use the data, omitting the high outlier, to give a 95% confidence interval for the decrease in penetrability of compressed soil relative to intermediate soil. compute degrees of freedom using the conservative method. interval: to