Question

The temperature on a mountain peak was 7 degreesFahrenheit (F) at 6:00 p.m. By 8:00 p.m., thetemperature had dropped to 0F. If the temperaturecontinued to drop at about the same rate, which isthebestestimate of the temperature at 11:00 p.m
A -20 / B. -14 / C -10 / D -9 /

Answer 1

Given:

The temperature on a mountain peak was 7°F at 6:00 p.m.

By 8:00 p.m., the temperature had dropped to 0°F.

To find:

The temperature at 11:00 p.m. if the temperature continued to drop at about the same rate.

Solution:

Time between 6:00 p.m. to 8:00 p.m. is 2 hours.

Change in temperature in 2 hours is -7°F.

Change in temperature in 1 hours is $-\dfrac{7}{2}^\circ$F.

Time between 8:00 p.m. to 11:00 p.m. is 3 hours.

Change in temperature in 3 hours is $3\times \dfrac{-7}{2}^\circ$F, i.e., $-\dfrac{21}{2}^\circ$F.

Now, the temperature at 11:00 p.m is:

$0-\dfrac{21}{2}=-10.5$

Therefore, the temperature at 11:00 p.m. is -10.5°F.

Note: All options are incorrect.