Question

how long can it swing?

	height dropped from (centimeters)	time swung (seconds)
test 1	10 cm	?
test 2	20 cm	49 sec
test 3	30 cm	72 sec

options: 25 sec, 55 sec, 85 sec, 65 sec

Explanation:

Step1: Analyze the trend

As the height dropped from increases (from 20 cm to 30 cm, an increase of 10 cm), the time swung increases from 49 sec to 72 sec, an increase of 23 sec. So when height decreases by 10 cm (from 20 cm to 10 cm), the time should decrease.

Step2: Estimate the time for 10 cm

The time for 20 cm is 49 sec. Since decreasing height by 10 cm should decrease time, and the increase from 20 to 30 was 23 sec, a decrease of around 24 - 25 sec from 49 sec makes sense. 49 - 24 = 25, so the time for 10 cm is likely 25 sec.

Answer:

25 sec