Faraz R. answered • 04/24/16

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y=Ce

^{kt}the Initial is the C. The final is the y. t = 4

.25=1.5e

^{4k}Divide .25 by 1.5 to get .167

So we do this now

.167=e

^{4k}Take a natural log of both sides to get

ln(.167=ln(e

^{4k}). ln and e cancel each other out since they are inverses of each other therefore the equation would look like this:ln(.167)=4k. Divide by 4 to solve for k. This is your rate constant. ln of .167 = -1.789761. You would divide this answer by 4 to get teh k. k= -.447

This is telling you that it is decaying.

Since you have k. You can now solve for the time it takes for this to get to .10.

.10=1.5e

^{-.447t}Follow the same steps. Divide .10 by 1.5. take ln of both sides then divide by -.447. You will have your answer. Thanks