= Solution
\b[The measured decay is approximately consistent with the predicted $198\ \mathrm{s^{-1}}$ loss rate.] Following rapid singlet-to-triplet population transfer, the unquenched <phosphorescence> intensity obeys
$$
I_P(t)=I_P(0)e^{-(k_P+k_D)t},\qquad \ln I_P=\ln I_P(0)-198t.
$$
A straight-line fit of $\ln I_P$ to the four times, expressed in seconds, gives
$$
\boxed{k_{\rm obs}=194.55\ \mathrm{s^{-1}},\qquad \tau_{\rm obs}=5.14\ \mathrm{ms},\qquad I_P(0)\simeq99.2.}
$$
This differs from $198\ \mathrm{s^{-1}}$ by about $1.7\%$. For example, using the first point and the predicted rate gives subsequent intensities about $67.3,55.2,45.3$, close to the supplied $66.3,56.2,45.3$. The data support the expected millisecond <exponential decay> to this precision. With no measurement uncertainties supplied, a formal statistical acceptance or rejection is not justified.
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