51. Recycling glass. In 2012, 34.1% of all glass containers were recycled. A beverage company used 400,000 lb of glass containers per year. After recycling, the amount of glass, in pounds, still in use after t years is given by N(t) = 400,000(0.341) '. (Source: www.gpi.org.)a) Find N(4), and explain its meaning. b) Find N'(4), and explain its meaning. c) When will 5% of the original amount of glass still be in use