Answer:
The specific gravity of the wood is 1.56
Explanation:
Given;
mass of the wood in water,
= 0.0175 kg
apparent mass of the wood and lead sinker submerged in water,
= 0.0765 kg
apparent mass with both the wood and the sinker both submerged in water, 
Mass of the lead sinker alone submerged in water;

Mass of the wood in the air;

Mass of water is calculated as follows;

The specific gravity of the wood is calculated as follows;

Therefore, the specific gravity of the wood is 1.56