The perimeter of a circular lawn is 37.68 meters, and a 2-meter-wide circular gravel road is paved outside. How many square meters is the area of this gravel road?

The perimeter of a circular lawn is 37.68 meters, and a 2-meter-wide circular gravel road is paved outside. How many square meters is the area of this gravel road?

This problem is actually to find the area of the ring
The radius of the round lawn is: 37.68 △ 3.14 △ 2 = 6m
The radius of the outer circle (plus the width of the path) is: 6 + 2 = 8m
The area of this stone road is: 3.14 × (8 × 8-6 × 6) = 87.92 square meters

There is a rectangular lawn in the square, 15 meters long and 10 meters wide. There is a 1 meter wide stone road around the lawn. What is the area of this stone road

The length and width are increased by 2 meters respectively, and the area of stone road is equal to (17x12) - (15x10) = 54 square meters
Another method (17x1 + 110x1) x2 = 54 square meters
Draw a picture and make a question

A rectangular lawn of 16 meters long and 9 meters wide is paved with a stone road of 1 meter wide,
If 60 kg of stone is needed per square meter, how many kg of stone is needed to pave this road?

What is the length of the stone road
16 + 2 = 18m
What is the width of the stone road
9 + 2 = 11 m
What is the area of the stone road
18 × 11-16 × 9 = 54 square meters
I want stones
54 × 60 = 3240 kg