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8. Given an annual rate of payment of f (t) = 35t2 at time t for 4 years and a force of interest of St = .06t2 . Which of the following formulas gives the AV of this continuously varying payments annuity? a) ( 35 +. ) e S.0672dr dt O b) ( ( 35 + 2 ) e for an dt 0 c) (35t2) eo [.0672dr dt O d) ( 35t2 ) ef . Ofmildr dt e) (35t2) e-06t at 0