Hello,
I have two geometric means (both of which are average antibody concentrations for a group of subjects calculated by multiplying all values and taking the nth root of this number, where n is the number of subjects with available data).

Group 1: Mean = 8985, confidence intervals = 5705–14150
67 people

Group 2: Mean = 7622, confidence intervals = 5486–10591
132 people

Overall mean: 8056.

Please could someone advise how I calculate the overall 95% confidence intervals?
Many thanks