$7$ Two soil testing machines are being evaluated by a geotechnical engineer to determine which machine his company should purchase. The data for the testing machines are listed in Table $9\mathrm{.}19.$ Using net present worth analysis, determine the incremental rate of return and compare it to the company MARR of $10\%$ to determine which machine should be purchased by the company.

TABLE $9\mathrm{.}19$

Data for Soil Testing Machine Alternatives

$\backslash$table$[[$Costs or Disbursements,Soil Testing Machine $1,$Soil Testing Machine $2],[$Initial cost$,$$$20,000\mathrm{.}00,$$$4,000\mathrm{.}00$