A line graph is shown where x-axis is 'Half-Life' ranges from 0 to 6 in increment of 1 and y-axis is 'Present of Isotope Remaining' ranges from 0 to 100 in increment of 25. A curve is drawn passing through five points: (0 comma 100), (1 comma 50) marked as one half, (2 comma 25) marked as one fourth, (3 comma 12.5) marked as one eighth, and (4 comma 6.25) marked as one sixteenth.