A company engaging in selling of laboratory equipment estimates that profit from sales should increase by $2,00,000$ per year if a mobile demonstration unit is built. A large unit with sleeping accommodation for the driver will cost $9,70,000$ while a smaller unit without sleeping cabin will be Rs$.6,30,000.$ Salvage values for the large and small units after $5$ years will be$,97,000$ and Rs$\mathrm{.}35000$ respectively. Lodging costs saved by the larger unit should amount $1,10,000$ annually, but its transportation costs will exceed those of the smaller unit by $31,000.$ With the money at $9\%$ should a mobile demonstration unit be built? And if so which size is preferable? Use net annual worth to determine which is better and show all the steps and working