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

A. 75

B. 76

C. 72

D. 74

Answer: Option A

Solution(By Examveda Team)

Given length and width of a square base plate of brass is x cm and 1 mm
Volume of the plate of square base = Area of base × height
$$\eqalign{ & = {x^2} \times \frac{1}{{10}} \cr & = \frac{{{x^2}}}{{10}}\,cu.cm. \cr} $$
According to the question,
$$\eqalign{ & \Rightarrow \frac{{{x^2}}}{{10}} \times 8.4 = 4725 \cr & \Rightarrow {x^2} = \frac{{4725 \times 10}}{{8.4}} \cr & \Rightarrow {x^2} = 5625 \cr & \Rightarrow x = \sqrt {5625} = 75\,cm \cr} $$