Question

The length of a rectangle is three times the breadth. If the minimum perimeter of the rectangle is 160 cm, then .

• A. $\mathrm{breadth}>20\mathrm{cm}$
• B. $\mathrm{breadth}\ge 20\mathrm{cm}$
• C. $\mathrm{length}<20\mathrm{cm}$
• D. $\mathrm{length}\le 20\mathrm{cm}$

Answer 1

The correct option is B $\mathrm{breadth}\ge 20\mathrm{cm}$

Let x cm be the breadth of the rectangle.
Therefore,
Length = 3x cm

Since the minimum perimeter
is 160 cm.
$\therefore \mathrm{Perimeter}\ge 160$
⇒ 2(Length + Breadth) ≥ 160
⇒ 2(3x + x) ≥ 160
⇒ 8x ≥ 160
⇒ x ≥ 20