In the school hall, chairs were arranged in rows of 13. During a function, 25 chairs were added to accommodate the number of people. The chairs were rearranged to form rows of 11. As a result, there were 5 more rows.
- How many chairs were there in the extra 5 rows?
- How many chairs were there in the school hall in the end?
|
First arrangement |
Second arrangement |
Number |
1 u |
1 u + 5 |
Value |
13 |
11 |
Total value |
13 u |
11 u + 55 |
(a)
Number of chairs in the extra 5 rows
= 5 x 11
= 55
(b)
Total number of chairs in the first arrangement
= 1 u x 13
= 13 u
Total number of chairs in the second arrangement
= 11(1 u + 5)
= 11 u + 55
If 25 chairs were included in the first arrangement, the total number of chairs in the first arrangement and the second arrangement will be the same.
13 u + 25 = 11 u + 55
13 u - 11 u = 55 - 25
2 u = 30
1 u = 30 ÷ 2 = 15
Number of chairs in the school hall in the end
= 15 x 13 + 25
= 195 + 25
= 220
Answer(s): (a) 55; (b) 220