Lamp posts were located at an equal distance of 21 m apart from one another, starting from the beginning of the road. Between every 2 lamp posts, there were 2 plants, planted 7 m apart.
- What was the distance between the first plant and the fourth plant?
- What was the distance between the sixth plant and the eighth plant?
- Given that the stretch of road was 126 m, how many plants were there?
Lamp post ↔ plant ↔ plant ↔ Lamp post ↔ plant ↔ plant ↔ Lamp post ↔ plant ↔ plant ↔ Lamp post
(a)
Length of each gap
= 21 ÷ 3
= 7
Distance between first and fourth plant
= 4 intervals
= 4 x 7
= 28 m
(b)
Distance between sixth and eighth plant
= 3 intervals
= 3 x 7
= 21 m
(c)
Distance between 2 lamp posts = 21 m
Number of sets of 21 m
= 126 ÷ 21
= 6
Number of plants
= 6 x 2
= 12
Answer(s): (a) 28 m; (b) 21 m; (c) 12