The area of the base of the brass-plate `=x^2` sq-cm.
Thickness = 1 mm =01 cm
`therefore` the volumes of the plate `=x^2xx 0.1 "cc "= x^2/10 "cc" `
, `therefore` the weight jof `(x^2)/(10)"cc" ` brass `= (8.4 xx x^2)/(100) 4725 ` or `84x^2` = 472500 or x `x^2 =5625 `
`x =sqrt(5625)= 75 `
Hence the value of x is 75