The ratio of the length and breadth of a rectangular parallelopiped is 5 : 3 and its height is 6 cm. If the total surface area of the parallelopiped be 558 sq. cm, then its length in dm is

Explanation:

Ratio of length : breadth

= 5 : 3

Total surface area of parallelopiped 558cm√2

2(lb+bh+hl)=558

2(5x×3x+3x×6+6×5x)

=558

2(15×2+18x+30x)=558

15x^2+45x=279

15x^2+48x−279=0

On solveing, x = 3

∴Length=5×3

=15cm=15\10=1.5dm