The level of radioactivity on the site of a nuclear explosion is decaying exponentially. The level measured in 1970 was found to be 0.7 times the level measured in 1960. What is the half-life. (the amount of years)

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- November 6th 2007, 09:52 PMmath34aradioactive
The level of radioactivity on the site of a nuclear explosion is decaying exponentially. The level measured in 1970 was found to be 0.7 times the level measured in 1960. What is the half-life. (the amount of years)

- November 6th 2007, 10:59 PMjanvdl
Radioactivity in 1970 =

Radioactivity in 1960 =

But

[Divide by y]

I think this is the rate at which it is decaying. I'll spend a little more time on it... :D

EDIT: Okay i got it! We now have the rate, so we want to know when

:D