The canton of Zurich plans a wildlife bridge with a timber structure. As such structures have been built with reinforced concrete so far, there is no experience with maintenance, repair and failure of such structures in the cantonal administration. Experts worry that undetected penetration of water into the structure from the soil cover (on top of the bridge) might lead to rotting timber and eventually failure of the entire structure, The suggest frequent inspections or additional sealing. To this aim, they developed two different variants of the bridge: Variant 1 "PBD only": A timber structure with a PBD sealing based on bitumen. Variant 2 "PBD & UHFB": A timber structure with a PBD sealing and an additional thin layer of UHFE (high performance fibre reinforced concrete). The expected costs for both variants are given below. The interest rate for discounting is 2% The expected service life is 50 years. Variant 1: PBD only construction costs (KCHF): 6'500 (occurrence: year 0) maintenance (kCHF): 7 (frequence: annually starting year 1) inspections (KCHF): 18 (frequence: annually starting year 1) renovation (KCHF): 300 (occurrence: year 25) minor repairs (KCHF): 9 (frequence: every two years starting year 2) Variant 2: PBD & UHFC construction costs (KCHF): 6'700 (occurrence: year 0) maintenance (KCHF): 7 (frequence: annually starting year 1) inspections (KCHF): 18 (frequence: every two years starting year 2) minor repairs (KCHF): 9 (frequence: every two years starting year 2) renovation (KCHF): 250 (occurrence: year 25) Answer the following questions. If calculations are required please respect the predefined units. You do not have to enter the units in your answer! Use always the unrounded values for the subsequent calculations! Pay attention to the convention for the signs! a. What is the net present value (NPV) for variant 1 "PBD only" [KCHF]? b. What is the annuity (a) for variant 1 "PBD only" [KCHF]? c. What is the net present value (NPV) for variant 2 "PBD & UHFC" [KCHF]? d. What is the annuity (a) for variant 2 "PBD & UHFC" [KCHF]?