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 9 tables.
- Find the number of tables if there are 100 chairs
- Find the number of chairs needed for 81 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 9 tables
= 9 x 2 + 2
= 20
(b)
Number of tables for 100 chairs
= (100 - 2) ÷ 2
= 49
(c)
Number of chairs for 81 tables
= 81 x 2 + 2
= 164
Answer(s): (a) 20; (b) 49; (c) 164