Question

there are 25 trees at equal distances of 5 metres in a line with a well, the distance of the well from the nearest tree being 10 metres.a gardener waters all the trees separately starting from the well and he returns to well after watering each tree to get water for the next.find the tatal distance the gardener will cover in order to water all the trees.

Answer 1

Gardner is standing near the well initially and he did not return to the well after
watering the last tree.
Distance covered by Gardner to water 1^st tree and return to the initial position =
10 m + 10 m = 20 m
Distance covered by Gardner to water 2^nd tree and return to the initial position =
15 m + 15 m = 30 m

Distance covered by Gardner to water 3^rd tree and return to the initial position =
20 m + 20 m = 40 m
∴Distances covered by the Gardner to water the plants are in A.P.
Here a = 20, d = 10
Distance covered to water 25^th tree = 20 + (25 – 1) x 10 = 20 + 240 =260
Total distance covered by the Gardner=25/2[(2x20+(25-1)x10] -260 =2470
Thus, the total distance covered by the Gardner is 2740m.