Find the limit as t approaches infinity of

N=(K*1/2e^(rt-(3/16)rkt))/(1+(1/2)e^(rt-(3/16)))

As t → ∞, e^-rt → 0 and e^rt → ∞

(K/2*0) / (1 + (1/2)∞) = 0

I suspect a typo, but maybe you can double-check.