Lamp posts were located at an equal distance of 9 m apart from one another, starting from the beginning of the road. Between every 2 lamp posts, there were 2 shrubs, planted 3 m apart.
- What was the distance between the first shrub and the 4th shrub?
- What was the distance between the sixth shrub and the tenth shrub?
- Given that the stretch of road was 60 m, how many shrubs were there?
Lamp post ↔ shrub ↔ shrub ↔ Lamp post ↔ shrub ↔ shrub ↔ Lamp post ↔ shrub ↔ shrub ↔ Lamp post
(a)
Length of each gap
= 9 ÷ 3
= 3
Distance between first and 4th shrub
= 4 intervals
= 4 x 3
= 12 m
(b)
Distance between sixth and tenth shrub
= 6 intervals
= 6 x 3
= 18 m
(c)
Distance between 2 lamp posts = 9 m
Number of sets of 9 m
= 60 ÷ 9
= 6 r 6
Number of shrubs at a distance of 6 m
= 6 ÷ 3
= 2
Number of shrubs
= 6 x 2 + 2
= 14
Answer(s): (a) 12 m; (b) 18 m; (c) 14