Analysis: First, look at the picture clearly, roll the rectangle along the long side to form a cylinder, and then seal the two circles, which is exactly an oil drum, so the length of the rectangle = the circumference of the circle.

Let the radius of a circle =X decimeter and the circumference of a circle =2X*3. 14= the length of a rectangle.

The length of rectangle+the diameter of circle = 16.56, that is 2X*3. 14+2X= 16.56.

If X=2, then the height of the bucket is 4 decimeters.

Therefore, the length of rectangle = 12.56 decimeter, the width is equal to 8 decimeter, and the volume of oil drum = bottom area * height = 2 * 3.14 * 2 * 8 =100.5 cubic decimeter.

1 cubic decimeter = 1 liter, so the oil weight is100 * 0.7 = 70kg.