You wish to measure the distance on a Mercator chart between a point in latitude 43°30'N and a point in latitude 40°30'N. To measure 30 miles at a time, you should set the points of the dividers at __________.

Correct Answer: Option B — 41°45' and 42°15'

On a Mercator chart, distance must be measured at the latitude of the segment being measured because the scale changes with latitude. To measure 30 miles between 43°30'N and 40°30'N, you must center your measurement at the mean latitude of 42°00'N, using 41°45' and 42°15'.