Answer:
[tex]43.1 ^{\circ}F[/tex]
Step-by-step explanation:
Give that for every 1000 feet increase in the height there is a drop of [tex]1.7 ^{\circ}F[/tex] in temperature.
So, the rate of temperature drop with respect to height, R = 1.7/1000 [tex]^{\circ}F/\text{ft}[/tex].
If the change in height is [tex]\Deltah[/tex][tex]\Delta h[/tex] feet, the temperature drop,
[tex]\Delta T= \Delta h R \;^{\circ}F\cdots(i)[/tex]
The temperature on the ground is 49.9 [tex]^{\circ}F[/tex].
At the ground, the height is 0, so the change in height, \Delta h when the plane reaches an altitude of 4,000 feet, is
\Delta h =4000-0=4000 feet
Now, from equation (i), the temperature drop
[tex]\Delta T= 4000 \times \frac {1.7}{1000}=6.8\;^{\circ}F.[/tex]
Hence, the temperature at an altitude of 4000 feet [tex]= 49.9-6.8=43.1 \;^{\circ}F[/tex].