Question

What fraction of a clockwise revolution does the hour hand of a clock turns through:
a) when it moves from 3 to 8?
b) when it moves from 3 to 9?
[2 MARKS]

Answer 1

Each option: 1 Mark

When the hour hand completes one complete revolution it completes 360 degrees.

a) When the hour hand moves from 3 to 6 it covers 90 degrees. When it moves from 6 to 8 it covers 60 degrees. So, the angle covered when hour hand moves from 3 to 8 is 150 degrees.

Fraction that it has moved = $\frac{150}{360}$ = $\frac{5}{12}$

b) When the hour hand of the clock moves from 3 to 9 it moves through two right angles.
So the angle it covers when it moves from 3 to 9 = 180 ${}^{\circ }$
Fraction that it has moved = $\frac{180}{360}$ = $\frac{1}{2}$