A stockist wants to make some profit by selling sugar. He contemplates about various methods. Which of the following would maximize his profit ?

Answer: Option B

We find the net profit in each case :
1 → In this case, profit = 10%
$$\begin{array}{rl}& 2\to \text{Profit}=\left(\frac{100}{900}\times 100\right)\%\\ & =11\frac{1}{9}\%\end{array}$$
3 → Let C.P. of sugar be Rs. 1 per kg

Then, he mixes 100 gm impurities and realizes the C.P. of 1.1 kg sugar by selling 1 kg of sugar.
S.P. of sugar = Rs. 1.10 per kg.
$$\begin{array}{rl}& \therefore \text{Profit}=\left(\frac{0.1}{1}\times 100\right)\%\\ & =10\%\end{array}$$
4 → Let C.P. of sugar be Rs. 1 per kg.
Since he weighs 950 gm instead of a kg, his actual
C.P. = Rs. 0.95
S.P. = 105% of Rs. 1 = Rs. 1.05
$$\begin{array}{rl}& \therefore \text{Profit}=\left(\frac{0.10}{0.95}\times 100\right)\%\\ & =10\frac{10}{19}\%\end{array}$$
Clearly, the maximum profit is earned when he used a 900 gm weight for a kg.