Page 50 - More Higher algebra
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Example 8:
13
Nitrogen-13 ( N) has a half-life of 9.965 minutes. If
13
you start with 22 grams of liquid N, how much will
be left after 15 minutes?
Isotope decay follows the expression,
− =
2
Make r the subject of the equation,
1
ln( − ) = ln ( )
2
1
− = ln ( )
2
or
ln(2) ln(2)
= = = 0.06956
9.965
The amount left after B seconds is,
= −0.06956
The keystrokes for this equation are,
46
