Answer:
To calculate the gradient from a contour map, you can follow these steps:
1. Draw a straight line between two points on the contour map.
2. Calculate the gradient by subtracting the elevation of the lower contour line on the line you drew from the elevation of the contour line at the other end of the line you drew.
3. Divide the answer by the distance in feet represented by the line you drew.
4. Multiply that number by 100 to give you the percent slope of the hill.
In your case, we have a maximum contour of **11,000ft** and a minimum contour of **850ft**. The scale of your map is **1:50,000** and the distance between points A and B is **12.5cm**.
To calculate the gradient between points A and B, we need to convert all units to feet. Since 1cm is equal to 196.85ft (50,000cm/254cm/inch), we can convert 12.5cm to feet by multiplying it by 196.85ft/cm which gives us **2,460ft**.
Next, we can calculate the difference in elevation between points A and B by subtracting the elevation of point B (850ft) from that of point A (11,000ft). This gives us **10,150ft**.
Finally, we can calculate the gradient using these values:
```
Gradient = (10,150ft / 2,460ft) x 100
= 412.20%
```
Therefore, the gradient between points A and B is approximately **412%**.
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