Mr Chin bought 3.8 kg of candy, nearest to 100g. What is the least amount of candy in the
bag to nearest kilogram.

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

Then why is the question on here if you know the answer