Year	Percent Remaining
0	100.0
5	88.7
10	78.7
15	69.9
20	62.0
25	55.0
30	48.8

a) Using technology, determine the equation of the line or curve of best fit that best represents this data. Is it a strong correlation (R - value)?

b) Use your equation to estimate how much Strontium-90 is left in year 40.