The table gives information about the cost per ounce, in £, of gold in January 2012, in January 2013, in January 2014 and in January 2015.
| Year | 2012 | 2013 | 2014 | 2015 |
|---|---|---|---|---|
| Cost per ounce (£) | 910 | 1020 | 1170 | 1540 |
| Chain base index number |
Calculate the chain base index numbers for the years 2013, 2014 and 2015 and write them in the table. Give each value correct to one decimal place.
Calculate the geometric mean of the chain base for the years 2013, 2014 and 2015. Give your answer correct to one decimal place.
Give an interpretation of your answer to part (b).
