To do this you need to find the lower bound
The lower bound is the minimum amount that would round up to the estimated value
3.8kg, measured to the nearest 100g
The degree of accuracy is to the nearest 100g
100/2 = 50g (0.05kg)
Lower bound 3.8 - 0.05 = 3.75kg
Therefore the least amount of candy you could have in the bag is 3.75kg