The table shows the amount of radioactive element remaining in a sample over a period of time.

Radioactive Decay Rate

Amount of Radioactive Sample Time

(grams)

(hours)

186. 0

0

147. 0

7

117. 0

14

93. 0

21

23. 3

63

Part 1: What is the half-life of the element? Explain how you determined this.

Part 2: How long would it take 320 g of the sample to decay to 2. 5 grams? Show your work or explain your answer.