There were some grey, brown and black pens in a box.
19 of the pens were brown. The ratio of the number of grey pens to the number of black pens was 3 : 5. There were 336 fewer brown pens than black pens.
- Find the ratio of the number of grey pens to the number of brown pens to the number of black pens in the box.
- How many black pens were there?
Brown |
Grey |
Black |
Total |
1 |
8 |
9 |
|
3 |
5 |
|
1 u |
3 u |
5 u |
9 u |
(a)
Grey : Brown : Black
3 : 1 : 5
(b)
Number of fewer brown pens than black pens
= 5 u - 1 u
= 4 u
4 u = 336
1 u = 336 ÷ 4 = 84
Number of black pens
= 5 u
= 5 x 84
= 420
Answer(s): (a) 3 : 1 : 5; (b) 420