A map is prepared with a scale of 1 : 1000 and a contour interval of 1 m. If the distance between two adjacent contours on the map is 10 mm, the slope of the ground between the adjacent contours is:

A nominal 30 m chain is found to be 10 cm too short throughout a measurement. If the recorded measured distance is 300 m, what is the actual true distance?

The length of a line measured by means of a nominal 20 m chain was found to be 610.2 m. If the actual length of the line is known to be 612.0 m, what was the actual length of the chain?