You are asked to date a shoreline that is found well above the margin of a present day lake. This is important paleoclimatic information for the basin, and we need to know how long ago the lake was at this elevation. You find a tree stump and sample its outer rings to date using the radiocarbon method. You have this analyzed at Beta Analytic Labs in Florida, and they report back that only 21% of the original ¹⁴C remains in the sample. 

i) How old is it, given that the half-life of ¹⁴C is 5730+40 years (as this was determined by a set of researchers at Cambridge, it is known in the community as the Cambridge half-life).

ii) Given the range of estimates of the half-life, calculate the associated range in age estimates. This will be a minimum estimate of the range for several reasons, in part because there will be additional error associated with error in the lab analysis.