The path of a rolling marble rolling off of a desk can be modeled by the parametric equations: x(t)= 2.5t y(t)=-16t^2+3, In these equations the horizontal and vertical positions of the marble x(t) and y(t) are in the feet and t is measured in seconds. A) The marble will hit the ground after how many seconds? B) Using your answer to A, how far horizontally from the edge of the table will the marble first hit the ground? C) The parametric equations above can be expressed as the following single rectangular equation:

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