Half-Life Problem: Solving A0e13K to Get K

[lwelch70]

1. Half life of a radioactive substance is 13 days. How long for 400 grams to decay to 300 grams? Solve algebraically and show all work. Give both exact answers and the answer rounded to 4 decimal places.



So I manipulated (1/2)A₀=A₀e^13K to obtain K = ln(1/2)/13

Where do I go from here?

 

[LCKurtz]

1. Half life of a radioactive substance is 13 days. How long for 400 grams to decay to 300 grams? Solve algebraically and show all work. Give both exact answers and the answer rounded to 4 decimal places.



So I manipulated (1/2)A₀=A₀e^13K to obtain K = ln(1/2)/13

Where do I go from here?

Put your known numbers back in the equation:

A = A₀e^(kt)