# After 280 days, the activity of a radioactive sample is 6000dps. The activity reduces to 3000dps after another 140days. What Is The initial activity of the sample in dps?

As given in the question:

The activity of the radioactive sample reduces to half in 140 days.

The half-life of the sample is 140 days.

280 days is its two half-lives.

So before two half-lives, its activity was

$$2^{6} * 6000$$ = 2000 dps

Therefore, The initial activity of the sample in dps is 2000 dps

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