Answer
$R = 4.91 \times 10^{16} \mathrm{s}^{-1}$
Work Step by Step
We need to find the concentration after the decay. We use the equation of the decay in the form
$$R =R_o e^{-\lambda t}$$
Now, plug the values for $R_o$ and the term $\lambda t=\left(8.89 \times 10^{-3} \mathrm{h}^{-1}\right)(48 \mathrm{h})=0.427$ into the decay equation to get $R$
$$R=\left(7.53 \times 10^{16} \mathrm{s}^{-1}\right) e^{-0.427}=\boxed{4.91 \times 10^{16} \mathrm{s}^{-1}}$$
