ACCRA, Sept 15 (Reuters) - Ghana’s economy grew 3.9% in the second quarter of 2021, the statistics service said on Wednesday. President Akufo-Addo told an investment conference earlier on Wednesday that the second quarter gross domestic product growth rate was at 8.9%. The statistics office did not comment on the figure given by the president. (Reporting by Christian Akorlie Writing by Cooper Inveen Editing by Bate Felix and Andrew Heavens)