Some amount of a radioactive substance (half-life =10 days ) is spread inside a room and consequently the level of radiation become `50` times the permissible level for normal occupancy of the room. After how many days will the room be safe for occupation?.

Explanation

To solve the problem, we need to determine how many days it will take for the radiation level in the room to drop to a safe level, given that the initial radiation level is 50 times the permissible level and the half-life of the radioactive substance is 10 days.

### Step-by-Step Solution:

1. **Understanding the Problem:**
- The half-life of the radioactive substance is given as \( t_{1/2} = 10 \) days.
- The initial radiation level is \( 50 \times A_0 \) (where \( A_0 \) is the safe concentration).
- We need to find the time \( t \) when the radiation level becomes \( A_0 \).
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