Question

The temperature (in degrees Celsius) as a function of time (in hours since noon) for a certain day in San Jose, Costa Rica, is graphed.
What is the approximate average rate at which the temperature decreases between
\[3{:}30\text{ pm}\] and
\[8{:}30\text{ pm}\]?
The first quadrant of a coordinate plane. The x-axis scales by zero point five and is labeled time since noon in hours. The y-axis scales by two and is labeled temperature in degrees celsius. The graph is a continuous curve. It starts at the y-intercept zero, twenty-four point five. Then it decreases at a non linear rate through the point three point five, twenty-four, the point five point five, twenty-two, the point eight point five, eighteen, and the point twelve, seventeen point nine. All values are estimates.
\[\small{1}\]
\[\small{2}\]
\[\small{3}\]
\[\small{4}\]
\[\small{5}\]
\[\small{6}\]
\[\small{7}\]
\[\small{8}\]
\[\small{9}\]
\[\small{10}\]
\[\small{11}\]
\[\small{4}\]
\[\small{8}\]
\[\small{12}\]
\[\small{16}\]
\[\small{20}\]
\[\small{24}\]
\[\small{28}\]
Choose 1 answer:
A
\[0.4\] degrees Celsius per hour
B
\[0.8\] degrees Celsius per hour
C
\[1.2\] degrees Celsius per hour
D
\[1.6\] degrees Celsius per hour

Answer 1

Average rate = (temperature change) / (time change) = (18 - 24) / (8.5 - 3.5) = -6 / 5 = -1.2°C/hour, so the temperature decreases about 1.2°C per hour. Answer: C.