Question

At the start of the road, a lamp post, a dust bin and a bench are placed together. Lamp post, dust bins

and benches are placed at intervals of 70 m, 56 m and 84 m respectively along a stretch of road 8 km
long. Whenever the three objects are placed together, they will be painted blue.
(a) How far away from the start of the road is the second set of the 3 blue objects?
(b) How many lamp posts are there between every 2 sets of blue objects?
No

Answer 1

70 = 2*5*7
56 = 2*2*2*7
84 = 2*2*3*7
Least common multiple of 70,56,84 = 2*2*2*3*5*7 = 840

The second set of blues is 2*840 = 1680 meters from the start