Discounted Cash Flow Further Aspects, Capital Rationing

Hi Sir Moffat, Couldn’t the company keep the $100 left over after investing in projects, as reserve for investing in the working capital for the year? Considering there might be higher inflation rates coming into play (although not a part of this practice question) which would mean the company might need some additional funds to buy materials in the upcoming years within the 3 year life of the project? Kindly let me know your thoughts.