Y9 Review

Custom Steel Products (CSP) is a company that provides construction materials to builders. One common structure is called a truss, as shown in the figure. A truss is made by fastening 1-foot steel rods together.

What area of mathematics would you consider as your main approach to this problem?

• Ratio and proportion

• Sequences

• Equations

• Constructions

If you approach this problem as a sequence, which of the following would be a useful starting point?

Based on your answer, carry out this step on the answer sheet.

• Setting up a table of total number of rods versus length of truss in feet

• Adding the next 3 feet to the diagram

• Redrawing the diagram where each top horizontal rod is split in the middle

• Setting up a table of number of horizontal rods versus total number of rods

How would you relate the truss characteristics to the vocab used in sequences?

What would be the first step in deciding what kind of sequence this is?

Based on your answer, carry out this step on the answer sheet.

• Divide each term by its position

• Find the difference between the terms

• Check if each pair of terms add up to give the next term

• Find the term-to-term rule

What kind of sequence is this?

• Geometric

• Fibonacci

• Linear

• Quadratic

What general formula describes this sequence?

Based on your answer, write down the formula on the answer sheet.

How many steel rods are in a truss 50 feet long?

Based on your answer, carry out this step on the answer sheet.

• 50

• 2497

• 199

• 253

The cost of one rod is $7.80. The allocated budget to build a truss is no more than $2000. To find out how long a truss can be built within this budget, what would you first do, and why?

Based on your answer, carry out this step on the answer sheet.

Find the length of truss that can be built within this budget.

Based on your answer, carry out this step on the answer sheet.

• 64 feet

• 1024 feet

• 1024.64 feet

• 64.35 feet