Chapter 1.4, Problem 117E

Doctors treated a patient at an emergency room from $2:00\text{ P}\text{.M}\text{.}$ to $7:00\text{ P}\text{.M}\text{.}$ The patient’s blood oxygen level $L$ (in percent) during this time period can be modeled by

$L=-0.270t^2+3.59t+83.1,2\le t\le 7$

where $t$ represents the time of day, with $t=2$ corresponding to $2:00\text{ P}\text{.M}\text{.}$ Use the model to estimate the time (rounded to the nearest hour) when the patient’s blood oxygen level was $93\%$ .