Mwanihi has 3.5 tins of sand. Each tin contains 0.5 kg of sand. Calculate the total mass of the sand in grams.

Mwanihi used 3.5 tins, and each tin contains $0.5\, \text{kg}$ of sand.

$$\text{Total mass in kg} = 0.5\, \text{kg/tin} \times 3.5\, \text{tins}$$ $$\text{Total mass in kg} = 1.75\, \text{kg}$$

There are $1000\, \text{g}$ in $1\, \text{kg}$.

$$\text{Total mass in g} = 1.75\, \text{kg} \times 1000\, \text{g/kg}$$ $$\text{Total mass in g} = 1750\, \text{g}$$

The total mass of the sand in the bucket was $\text{1750 g}$.