Question

The perimeter of rectangle PQRS is 70 cm. If PQ : QR = 3 : 4, then find QR.

Answer 1

let sides be 3x and 4x , then
2(l+b)= perimeter
-> 2(3x+4x) = 70
-> 2×7x =70
-> 14x = 70
-> x= 5
therefore QR = 4x = 4 × 5 = 20cm.

Answer 2

Let the sides of the rectangle be 3x & 4x respectievely ( As given 3:4 )
Then ;
Perimeter of Rectangle = 2(l + b)
so; 2 ( 3x + 4x ) = 70
2 ( 7x ) = 70
7x = 70/2
= 35
then x = 35/7
theirfore x = 5
then side QR ( As it is taken as the breadth ) =;
4x = 5×4 = 20