The internal rate of return method is used by Royston Construction Co$.$ in analyzing a capital expenditure proposal that involves an investment of $$48,592$ and annual net cash flows of $$16,000$ for each of the $4$ years of its useful life.

Present Value of an Annuity of $$1$ at Compound Interest

Year $6\%10\%12\%15\%20\%$

$10\mathrm{.}9430\mathrm{.}9090\mathrm{.}8930\mathrm{.}8700\mathrm{.}833$

$21\mathrm{.}8331\mathrm{.}7361\mathrm{.}6901\mathrm{.}6261\mathrm{.}528$

$32\mathrm{.}6732\mathrm{.}4872\mathrm{.}4022\mathrm{.}2832\mathrm{.}106$

$43\mathrm{.}4653\mathrm{.}1703\mathrm{.}0372\mathrm{.}8552\mathrm{.}589$

$54\mathrm{.}2123\mathrm{.}7913\mathrm{.}6053\mathrm{.}3532\mathrm{.}991$

$64\mathrm{.}9174\mathrm{.}3554\mathrm{.}1113\mathrm{.}7853\mathrm{.}326$

$75\mathrm{.}5824\mathrm{.}8684\mathrm{.}5644\mathrm{.}1603\mathrm{.}605$

$86\mathrm{.}2105\mathrm{.}3354\mathrm{.}9684\mathrm{.}4873\mathrm{.}837$

$96\mathrm{.}8025\mathrm{.}7595\mathrm{.}3284\mathrm{.}7724\mathrm{.}031$

$107\mathrm{.}3606\mathrm{.}1455\mathrm{.}6505\mathrm{.}0194\mathrm{.}192$

a$.$ Determine a present value factor for an annuity of $$1,$ which can be used in determining the internal rate of return. If required, round your answer to three decimal places.

fill in the blank $1$ of $1$

b$.$ Using the factor determined in part $($a$)$ and the present value of an annuity of $$1$ table above, determine the internal rate of return for the proposal.