The diagram shows the number of tables (T) and the number of chairs (P) around the tables.
- Find the number of chairs needed when there are 13 tables.
- Find the number of tables if there are 42 chairs
- Find the number of chairs needed for 133 tables.
(a)
Pattern for the number of chairs
1 table: 1 x 2 + 2 = 4
2 tables: 2 x 2 + 2 = 6
3 tables: 3 x 2 + 2 = 8
Formula
Number of chairs = Number of tables x 2 + 2
Number of chairs for 13 tables
= 13 x 2 + 2
= 28
(b)
Number of tables for 42 chairs
= (42 - 2) ÷ 2
= 20
(c)
Number of chairs for 133 tables
= 133 x 2 + 2
= 268
Answer(s): (a) 28; (b) 20; (c) 268