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radioactivity decay:Let q represent a mass of radioactive radium(226^Ra)(in grams ), whose half life is 1620 years.

the quantity of radium present after t years is

Q=25(1/2)^t/1620.

(a)Determine the initial quantity (when t=0)

(b) Determine the quantity present after 100 years

(c) graph the function over the interval t=0 to t=5000

There should be parentheses around the exponent:

Q = 25(½)^(t/1620)

The initial quantity is 25 g.

The quantity after 100 years is approximately 23.95 g:

http://www.flickr.com/photos/dwread/8451347843/

The quantity after 5000 years is approximately 2.94 g

http://www.flickr.com/photos/dwread/8451347809/

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