First, you’ll need to find the area of the large window, and divide it by the area of the small window. This will tell us how many small windows we need to make the large window.
The area of the larger window is 3.6 x 3.6 = 12.96 sq. m, and the area of the smaller window is 7.2 x 7.2 = 51.84 sq. cm. Before we divide, we’ll need to make sure we’re working in the same units, so let’s convert the area of the large window to centimeters. 3.6 m = 3.6 x 100 = 360 cm, so the area of the large window in centimeters is 360 x 360 = 129,000 sq. cm.
Dividing 129,000 by 51.84, we find that one big window can fit 129,000/51.84 = 2,500 small windows in it.
Knowing that each small window weighs 100 grams, the total weight needed for the big window is 2,500 x 100 = 250,000 grams, or 250 kilograms.