Posted by **Sarah** on Tuesday, April 12, 2011 at 11:24pm.

How much of a 6gram sample of silver-105m would remain after 4 minutes?

Half life=7.2 minutes

- Half-Lifes -
**DrBob222**, Tuesday, April 12, 2011 at 11:35pm
k = 0.693/t_{1/2}

Substitute k into the equation below.

ln(No/N) = kt.

No = 6

N = unknown

k = from above

t = 7.2 min

I get approximately 4 g remaining.

- Half-Lifes -
**Sarah**, Tuesday, April 12, 2011 at 11:41pm
Great! But, so that I can understand it in the future, can you tell me what the value of k is a little more clearly? how do you do a subscript of 1/2?

- Half-Lifes -
**DrBob222**, Wednesday, April 13, 2011 at 12:34am
The half life is given in the problem (last line you typed) of 7.2 minutes.

I write a t_{1/2}

To turn on subscript type < followed by sub followed by >. Then type the 1/2. To turn subscript off type < followed by /sub followed by >

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