College

A patient has an illness that typically lasts about 24 hours. The temperature, [tex] T(t) [/tex], in degrees Fahrenheit, of the patient [tex] t [/tex] hours after the illness begins is given by:

[tex] T(t) = -0.01t^2 + 0.218t + 97.6 [/tex]

Round all answers to one decimal place.

1. When does the patient's temperature reach its maximum value?
- Answer: After [tex]\square[/tex] hours.

2. What is the patient's maximum temperature during the illness?
- Answer: [tex]\square[/tex] degrees Fahrenheit.

Answer :

We are given the temperature function

[tex]$$
T(t) = -0.01t^2 + 0.218t + 97.6,
$$[/tex]

where [tex]\( t \)[/tex] is in hours. Since the coefficient [tex]\( a = -0.01 \)[/tex] is negative, the quadratic function opens downward and therefore reaches a maximum at its vertex.

Step 1. Find the time at which the maximum occurs.

The time corresponding to the vertex of a quadratic function of the form

[tex]$$
T(t) = at^2 + bt + c
$$[/tex]

is given by

[tex]$$
t = -\frac{b}{2a}.
$$[/tex]

Substitute the values [tex]\( a = -0.01 \)[/tex] and [tex]\( b = 0.218 \)[/tex]:

[tex]$$
t = -\frac{0.218}{2(-0.01)} = \frac{0.218}{0.02} \approx 10.9.
$$[/tex]

Rounded to one decimal place, the maximum temperature is reached after [tex]\( 10.9 \)[/tex] hours.

Step 2. Find the maximum temperature.

Substitute [tex]\( t = 10.9 \)[/tex] into the function:

[tex]$$
T(10.9) = -0.01(10.9)^2 + 0.218(10.9) + 97.6.
$$[/tex]

Evaluating this expression gives approximately

[tex]$$
T(10.9) \approx 98.7881.
$$[/tex]

Rounded to one decimal place, the maximum temperature is [tex]\( 98.8^\circ \)[/tex]F.

Final Answers:

- The patient’s temperature reaches its maximum after [tex]\( 10.9 \)[/tex] hours.
- The patient’s maximum temperature is [tex]\( 98.8^\circ \)[/tex]F.