Answer:
The temperature at 5376 ft is approximately 63°F
The assumption made was that the temperature varies linearly with elevation
Explanation:
The parameters given are;
Temperature at 6288 feet = 56°F = 286.5
Temperature at 2041 feet = 87°F = 303.71
We are to find the temperature at 5376 feet
Let the temperature be the y-coordinate value and the elevation be the x-coordinate value, to find the temperature, we have the temperature gradient given by the relation;

The temperature at 5376 ft will be the temperature at 2041 added to the decrease in temperature from climbing to 5376 ft
The increase in elevation is 5376 - 2041 = 3335 ft
The decrease in temperature = 3335 ft × (-4.05 × 10⁻³) K/ft = -13 .5 K
The temperature at 5376 ft will then be 303.71 - 13.5 = 290.196 K = 62.68°F ≈ 63°F
The assumption made was that the decrease in temperature with elevation is linear.