Each of the figures is made up of 1-cm wooden rods.
The table shows the number of wooden rods used to make the figures and their perimeters.

1. Find the number of wooden rods in Figure 18.
2. What is the perimeter of Figure 75?
3. Which figure requires a total number of 3367 wooden rods?

(a)
Pattern for the number of wooden rods
Figure 1: 1 x 8 + 7 = 15
Figure 2: 2 x 8 + 7 = 23
Figure 3: 3 x 8 + 7 = 31

Formula:
Number of wooden rods = Pattern number x 8 + 7

Number of wooden rods in Figure 18
= 18 x 8 + 7
= 151

(b)
Pattern for the perimeter of the figure
Figure 1 = 1 x 2 + 7 = 9
Figure 2 = 2 x 2 + 7 = 11
Figure 3 = 3 x 2 + 7 = 13

Formula:
Perimeter of the figure = Pattern number x 2 + 7

Perimeter of figure 75
= 75 x 2 + 7
= 157

(c)
Figure number x 8 + 7 = 3367
Figure number x 8 = 3367 - 7 = 3360
Figure number = 3360 ÷ 8 = 420

Answer(s): (a) 151; (b) 157; (c) 420