There were some grey, brown and black pencils in a box.
112 of the pencils were brown. The ratio of the number of grey pencils to the number of black pencils was 4 : 7. There were 258 fewer brown pencils than black pencils.
- Find the ratio of the number of grey pencils to the number of brown pencils to the number of black pencils in the box.
- How many black pencils were there?
Brown |
Grey |
Black |
Total |
1 |
11 |
12 |
|
4 |
7 |
|
1 u |
4 u |
7 u |
12 u |
(a)
Grey : Brown : Black
4 : 1 : 7
(b)
Number of fewer brown pencils than black pencils
= 7 u - 1 u
= 6 u
6 u = 258
1 u = 258 ÷ 6 = 43
Number of black pencils
= 7 u
= 7 x 43
= 301
Answer(s): (a) 4 : 1 : 7; (b) 301