Question

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

Answer 1

3240 meters.

(((25*26)/2)-1)10

Answer 2

Let the number of trees be denoted by T where, T belongs to [ 1 , 25 ], i.e., 1 to 25.
So, if the garderner is going to water the 1st tree then T = 1, if 2nd tree then T = 2 and so on.....
Now, if he starts from the well then, he will have to travel 10m to the 1st tree and back 10m to the well,
So, From the well to the tree and then to the well then the distances are going to be;
1st tree = 2 [ 10m + (T - 1)*5m ] = 2 ( 10m ) = 20m
2nd tree = 2 [ 10m + (T - 1)*5m ] = 30m
3rd tree = 40m
4th tree = 50m
5th tree = 60m
6th tree = 70m
7th tree = 80m
8th tree = 90m
9th tree = 100m
10th tree = 110m
11th tree = 120m
12th tree = 130m
13th tree = 140m
14th tree = 150m
15th tree = 160m
16th tree = 170m
17th tree = 180m
18th tree = 190m
19th tree = 200m
20th tree = 210m
21st tree = 220m
22nd tree = 230m
23rd tree = 240m
24th tree = 250m
And, finally the 25th tree = 10m + (T - 1)*5m = 130m As, the gardener will not have to go back to the well..... So, half the distance will be covered.....
Now, we have all the distances, on adding these we can easily get that the gardener has to travel 3370m in order to water all the 25 trees.

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THERE YOU GO!!!.....