Tuesday, October 5, 2010
5.Silvio wants to cover the stairs of his basement, There are 14 treads, or steps, and 14 risers. Each step is 90 cm wide and 24 cm deep. Each riser is 90 cm and 18 cm high. The diagram shows some of the stairs
A. What is the surface area of the step treads?
24cmx90cm = 2160cm²
2160cm² = one step tread
2160cm² x 14 = 30240cm²
Surface Area of all treads = 30240cm²
B. What is the surface area of the risers ?
18cm x 90 cm = 1620cm²
1620cm² = one riser
1620² cm x 14 = 22680cm²
Surface Area of all risers = 22680cm²
C.What is the total surface area of the part of the stairs that Silvio wants to cover?
22680cm² + 30240cm² = 52920cm²