In the school hall, chairs were arranged in rows of 12. During a function, 30 chairs were added to accommodate the number of people. The chairs were rearranged to form rows of 10. As a result, there were 4 more rows.
- How many chairs were there in the extra 4 rows?
- How many chairs were there in the school hall in the end?
|
First arrangement |
Second arrangement |
Number |
1 u |
1 u + 4 |
Value |
12 |
10 |
Total value |
12 u |
10 u + 40 |
(a)
Number of chairs in the extra 4 rows
= 4 x 10
= 40
(b)
Total number of chairs in the first arrangement
= 1 u x 12
= 12 u
Total number of chairs in the second arrangement
= 10(1 u + 4)
= 10 u + 40
If 30 chairs were included in the first arrangement, the total number of chairs in the first arrangement and the second arrangement will be the same.
12 u + 30 = 10 u + 40
12 u - 10 u = 40 - 30
2 u = 10
1 u = 10 ÷ 2 = 5
Number of chairs in the school hall in the end
= 5 x 12 + 30
= 60 + 30
= 90
Answer(s): (a) 40; (b) 90