Question

If the sides of an equilateral triangle are increased by $20\%,30\%$and$50\%$ respectively to form a new triangle, then the increase in the perimeter of the triangle is:

• A. $25\%$
• B. $33\frac{1}{3}\%$
• C. $75\%$
• D. $100\%$

Answer 1

The correct option is B $33\frac{1}{3}\%$

Let the sides of equilateral triangle be $100cm$.Then perimeter of triangle $=100+100+100=300$
Then the sides of an equilateral triangle are increased by $20\%$, $30\%$ and $50\%$ respectively
$\therefore$ new sides are $120,130$ and $150cm$
Then parimeter of new triangle $=120+130+150=400$
Then the increase in the perimeter of the triangle $=400-300=100cm$
% of increase in the perimeter of the triangle $=\frac{100\times 100}{300}=33\frac{1}{3}$%