Map Reading and Interpretation Questions and Answers

Answer: A

Correct answer: clockwise from north through 360 degrees

The whole-circle system measures every bearing in one direction from one reference, so there is no ambiguity and no quadrant to record. That is what distinguishes it from the older quadrantal system, in which a bearing is given as an angle from north or south towards east or west.

Answer: B

A back bearing differs from the forward bearing by 180 degrees, and since 070 is less than 180 the figure is added rather than subtracted. Subtracting instead would give a negative value, which is the usual error and an immediate sign that the wrong rule has been applied.

Answer: C

Because 300 exceeds 180, the 180 degrees is subtracted rather than added, giving 120. Adding would produce 480 degrees, which must then be reduced by a full circle of 360 to reach the same answer of 120, so either route works if it is followed through.

Answer: D

Correct answer: False

The rule is to add 180 if the forward bearing is less than 180, and to subtract 180 if it is 180 or more - since a bearing must lie between 0 and 360. Adding 180 to a bearing of 250 would give 430, which is not a bearing at all.

Answer: A

Correct answer: turning it so its north matches the ground

An oriented map has its features in the same relative directions as the features around the reader, so a hill drawn to the left of the road is actually to the left. Everything else in map reading - identifying features, taking bearings, following a route - is easier once it has been done.

Answer: B

Bearings to identifiable landmarks are plotted back from those landmarks, and the observer stands where the lines meet. Two landmarks suffice in principle, but three are used so the small triangle they form reveals the error.

Answer: C

Correct answer: a triangle of error

Three resection lines rarely meet exactly, because each bearing carries a small error. The resulting triangle bounds the observer’s position, and the smaller it is the better the fix. A large triangle indicates a mistake rather than mere imprecision - commonly a misidentified feature or a bearing taken to the wrong point.

Answer: D

A small wheel run along the line accumulates its true length, which a straight rule cannot give for a curving road or river. A piece of thread laid along the route and then straightened does the same job less precisely.

Answer: A

Twenty-four centimetres at 50,000 times is 1,200,000 centimetres, which is 12 kilometres. Following the curves rather than measuring straight across is what makes the figure useful for planning a journey, since a vehicle must travel the road as it lies.

Answer: B

Roads bend around obstacles and follow gentler gradients, so the travelled distance commonly exceeds the direct one by a fifth or more. In broken country the difference can be much greater still, which is why a route is measured along its course rather than across it.