A radioactive element decays by `beta-emission`. A detector records n beta particles in 2 s and in next 2 s it records 0.75 n beta particles. Find mean life correct to nearest whole number. Given ln `|2| = 0.6931`, ln `|3|=1.0986`.

Explanation

To solve the problem, we will follow these steps:

### Step 1: Understand the decay process
We know that the number of radioactive particles decreases over time according to the equation:
\[ N(t) = N_0 e^{-\lambda t} \]
where:
- \( N(t) \) is the number of particles remaining at time \( t \),
- \( N_0 \) is the initial number of particles,
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