Question

The perimeter of a square is 240 cm.The ratio of length is to breadth is 7:5 .Write the area

Answer 1

given ratio of lengthand braedth is 7:5
let us take x as a constant
then,
length=7x
breadth=5x
perimeter of rectangle=240cm
                          2(l+b)=240
                     2(7x+5x)=240
                              24x=240
                                  x=240/24
                                  x=10cm
by substituting x=10cm in length and breadth
                       length=70cm
                        breadth=50cm
area of rectangle=length×breadth
                           =70×50
area of rectangle=3500cm²

Answer 2

Perimeter of the rectangle = 240 cm
Ratio of length is to breadth = 7 : 5

The semi-perimeter of the rectangle = 240 / 2
                                                          = 120
Total number of parts in ratio = 7+5 = 12
Each part = 120 / 12 = 10

.'. The length of rectangle = 7 parts of 120
                                         = 10 * 7
                                         = 70 cm
.'.The breadth of rectangle = 5 parts of 120
                                           = 10 * 5
                                           = 50 cm

.'.Area of the rectangle = length* breadth
                                     = 50 * 70
                                     = 3500 square cm
                     .'. Answer = 3500 square cm