Question

A pole, 90 cm long, is painted green, white, and black in the ration 3:4:2. What length of the pole is painted black?

Write a teacher's solution with a bar diagram.​

Answer 1

3u + 4u + 2u = 9u
9u = 90
1u = 90/9 = 10

since black is 2u ( from the ratio given)
2u = 10 x 2 = 20

Answer : 20cm of the pole is painted black.

The bar diagram is in the picture :)