Hint:
Distances between trees and well are in A.P.
Given:
The distance of well from its nearest tree is 10 metres
Distance between each tree is 5 metres.
So,
In A.P
The first term is 10 metres and the common difference is 5 metres.
a = 10 & d = 5
The distances are in the following order
10, 15, 20… (30 terms)
The farthest tree is at a distance of a + (30 – 1) ×d
l = 10 + (29) ×5
L = 155 metres.
Total distance travelled by the Gardner = 2×Sum of all the distances of 30 trees from
the well.
= 15 × 165 metres
= 2475 metres.
Total distance travelled by the Gardner is 2 × 2475 metres.
∴The total distance travelled by the Gardner is 4950 metres.