A plate on square base made of brass is of length $$x\ cm$$ and width 1 mm. The plate weight 4725 gm. If 1 cubic cm of brass weighs 8.4 gram, then the value of x is:

Thickness of brass plate = 1 mm = 0.1 cm

As the plate is in square shape, so the length and breath are same.

=> Length = Breadth = $$x$$ cm

Volume = $$(x\times x\times0.1)=\frac{x^2}{10}$$ $$cm^3$$

Given that 1 cu cm of brass has weight = 8.4 g

Thus, total weight = $$8.4\times\frac{x^2}{10}=0.84x^2$$ gram

According to ques, => $$0.84x^2=4725$$

=> $$x^2=\frac{4725}{0.84}=5625$$

=> $$x=\sqrt{5625}=75$$ cm

=> Ans - (D)