CLASS-7
WHEN LENGTHS OF THE SIDES ARE GIVEN

Area = l x b

         = 270cm x 85cm

         = 22950 cm².     (Ans.)

Example.2) Find the perimeter and area of a square whose each side is 6.5cm.

Ans.)

Perimeter = 4 x a

= 4 x 6.5cm = 26cm.

Area = a²

= (6.5)² cm² = 42.25 cm²         (Ans.)

Example.3) Arnold walks around a rectangular park with length 110m and width 70m at the rate of 4 km/hour. In how much time will he complete 5 rounds of park??

Ans.) Distance cover by Arnold in one round of the park is perimeter of the rectangular park is perimeter of the park = 2 (length + width)

                                                  = 2 (110 + 70)m

                                                  = (2 X 180) = 360m

Distance covered by 5 rounds = 5 X 360m = 1800m

Walking speed of Arnold is 4 km/hour = 4000 meter/60 minutes

                                          = 200/3 meter/minutes

Now, as per the condition -

Arnold, travels 200/3 meter by 1 minutes

Arnold, travels 1 meter by = 1 ÷ 200/3 = 1 X 3/200 = 3/200 minutes

Arnold, travels 1800 meter by = 3/200 X 1800 = (3 X 9) minutes

                                                    = 27 minutes

Hence, Arnold will completer 5 rounds of park by 27 minutes.   (Ans.)