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: Find angle between adjacent points

The total angle around a circle is $360^{\circ}$. Since there are 9 equally - spaced points, the angle between adjacent points is $\frac{360^{\circ}}{9}=40^{\circ}$.

Step2: Count number of intervals from A to E

Counting clockwise from A to E, there are 4 intervals.

Step3: Calculate total degrees of turn

Multiply the number of intervals by the angle between adjacent points. So the dial has to turn $4\times40^{\circ} = 160^{\circ}$.

Answer:

$160$