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 13.
2. What is the perimeter of Figure 152?
3. Which figure requires a total number of 1215 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 13
= 13 x 8 + 7
= 111

(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 152
= 152 x 2 + 7
= 311

(c)
Figure number x 8 + 7 = 1215
Figure number x 8 = 1215 - 7 = 1208
Figure number = 1208 ÷ 8 = 151

Answer(s): (a) 111; (b) 311; (c) 151