A proposed nuclear power plant will cost $$2\mathrm{.}3$ billion to build and then will produce cash flows of $$310$ million a year for $15$ years. After that period $($in year $15),$ it must be decommissioned at a cost of $$910$ million.

Note: Negative amounts should be indicated by a minus sign. Do not round intermediate calculations. Enter your answers in billions rounded to $3$ decimal places.

a$.$ What is the NPV of the project if the discount rate is $4\%?$

Net present value billion

b$.$ What is the NPV of the project if the discount rate is $17\%?$

Net present value

billion