I'm not very sure how to tackle this sort of problem:
It is as follows:
At a groceries store there is a two pan scale and two weighs which are of $250\,g$ and the other of $500\,g$. It is known that the store has only $5\,kg$ of sugar on sale. Find the least number of weigh trials that must be made in order to fill an order of two sacks containing $2.625\,kg$ of sugar and the other $2.375\,kg$.
The alternatives given in my book are as follows:
$\begin{array}{ll} 1.&\textrm{1 trial}\\ 2.&\textrm{2 trials}\\ 3.&\textrm{3 trials}\\ 4.&\textrm{4 trials}\\ 4.&\textrm{5 trials}\\ \end{array}$
In this problem I'm sort of lost. Typically what I've attempted to do was that I can balance out half of the sack which has 5\,kg of the sugar hence in one sack I end up with $2500\,g$ and the other $2500\,g$.
I've attempted to add the two weighs given $500+250=750$ but this doesn't exactly produce a result which I could use. How exactly should I proceed in these kinds of problems. Can someone help me?.
Since I'm a slow learner, I'd like to get a very detailed explanation and a strategy on how to solve this sorts of problems.