There were some grey, brown and black notebooks in a box.
110 of the notebooks were brown. The ratio of the number of grey notebooks to the number of black notebooks was 4 : 5. There were 276 fewer brown notebooks than black notebooks.
- Find the ratio of the number of grey notebooks to the number of brown notebooks to the number of black notebooks in the box.
- How many black notebooks were there?
Brown |
Grey |
Black |
Total |
1 |
9 |
10 |
|
4 |
5 |
|
1 u |
4 u |
5 u |
10 u |
(a)
Grey : Brown : Black
4 : 1 : 5
(b)
Number of fewer brown notebooks than black notebooks
= 5 u - 1 u
= 4 u
4 u = 276
1 u = 276 ÷ 4 = 69
Number of black notebooks
= 5 u
= 5 x 69
= 345
Answer(s): (a) 4 : 1 : 5; (b) 345