Some tables and chairs are arranged as shown:
- How many chairs are there in Figure 9?
- How many tables are needed for 92 chairs?
(a)
Pattern for the number of chairs
Figure 1: 1 x 2 + 2 = 4
Figure 2: 2 x 2 + 2 = 6
Figure 3: 3 x 2 + 2 = 8
Formula:
Number of chairs = Figure number x 2 + 2
Number of chairs for Figure 9
= 9 x 2 + 2
= 20
(b)
Pattern for the number of tables
Figure 1: 1
Figure 2: 2
Figure 3: 3
Formula:
Number of tables = Figure number
Figure number for 92 chairs
= (92 - 2) ÷ 2
= 90 ÷ 2
= 45
Number of tables = 45
Answer(s): (a) 20; (b) 45