A certain block weighs 15 N in air. But is weighs only 12 N when completely immersed in water. When immersed completely in another liquid, it weighs 13 N. Calculate the relative density of (i) the block and (ii) the liquid.

Explanation

To solve the problem, we need to calculate the relative density of the block and the liquid based on the given weights in air and when immersed in water and another liquid.

### Step-by-Step Solution:

1. **Identify the Given Data:**
- Weight of the block in air (W_block_air) = 15 N
- Weight of the block in water (W_block_water) = 12 N
- Weight of the block in another liquid (W_block_liquid) = 13 N
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