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January 28, 2015

January 28, 2015

Posted by **marjani** on Saturday, August 27, 2011 at 9:00am.

- chemistry -
**DrBob222**, Saturday, August 27, 2011 at 1:59pmThis is the long way but I would do this.

ln(No/N) = kt

Substitute

No = 100 (just make up any number)

N = 25 (25% of whatever you picked for No)

k = solve for this

t = 40 minutes.

Then substitute k into

k = 0.693/t_{1/2}and solve for t_{1/2}.

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