Question 23.94

64. Indium is an element (atomic number 49) used in solar cells and in the screens of tablet computers and cell phones; refined indium costs about $600 per kilogram. The current world reserves are about 11,000 metric tonnes, with annual world consumption of about 770 metric tonnes.

  1. What is the static reserve of indium?
  2. World demand increased from 570 tonnes to 770 tonnes from 2008 to 2013. What was the average annual compounded rate of increase?
  3. Suppose that demand for indium increases at 6% per year for the foreseeable future. What is the corresponding exponential reserve?