Which of the following statements A-D are correct? A. 5% of (25% of 1600) is 50. B. 0.15% of 33⅓% of…

Statement A is incorrect because 25% of 1600 is 400, and 5% of 400 is 20 (not 50). Statement B is correct since $33\frac{1}{3}\%$ of 10,000 is $\frac{10000}{3}$, and $0.15\%$ of $\frac{10000}{3}$ equals $\frac{0.15}{100} \times \frac{10000}{3} = 5$. Statement C is correct because $R = \frac{5400 \times 100}{15000 \times 3} = 12\%$. Statement D is incorrect because $\frac{x}{3} = \frac{y}{4} = \frac{z}{5}$ implies $x : y : z = 3 : 4 : 5$. Therefore, only B and C are correct.