On the number line shown, the marks are equally spaced. What number does the arrow point to?
Text description of the figure
A number line with equally spaced tick marks. The leftmost tick is labelled 0 and the rightmost is labelled 60, with five unlabelled ticks evenly spaced between them. An arrow points to the fourth tick from the left.
Hints
Take them one at a time. The first gives nothing away.
1A nudge
Work out what one gap is worth first.
2The strategy
Count the gaps between 0 and 60, not the ticks. Dividing 60 by the number of gaps gives the value of one step, and then you count steps to the arrow.
3The full solution
There are six gaps between 0 and 60, so each gap is worth 10. The arrow sits at the third tick after zero, which is three gaps along, so it points to 30.
Solution— no shortcut on this one
First find the scale. From 0 to 60 there are six equal gaps, so one gap is 60 divided by 6, which is 10. The arrow is three gaps to the right of zero, so it points to 3 times 10 = 30. The transferable idea: on any scale, count the gaps and not the marks.
Why this is on the test: Reading a scale correctly is worth more marks across a whole paper than any single clever technique, and gaps-versus-ticks is where it is lost.