Question

a circular dial has nine equally spaced points, as shown. point a is on the top of the dial. suppose that the dial is turned clockwise until point e is on top. how many degrees does the dial have to turn?

Explanation:

Step1: Calculate angle between each point

The total angle in a circle is 360°. There are 9 equally - spaced points. So the angle between each adjacent point is $\frac{360}{9}=40^{\circ}$.

Step2: Count number of points from A to E

Counting clock - wise from point A to point E, there are 4 points.

Step3: Calculate total angle of rotation

The total angle of rotation is the number of points times the angle between each point, so $4\times40 = 160^{\circ}$.

Answer:

160