in orchard there are 17 Mango trees in the First row 15 in the second 13 in the third and so on there are three mango trees in last row how many rows of trees are there in the Orchard
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Answer:
It's in arithmetic progression because
No of trees in the first row - No of trees in the second row = d
d = 2
No of trees in the second row - No of trees in the third row = d
d = 2
Both are satisfying the value of d
No of rows:
nth term = a + (n-1)d
17 + (n-1)(-2) = 3
17 - 2n + 2 = 3
2n = 16
n = 8
No of rows = 8
No of trees:
17 + 15 + 13 + 11 ...... + 3
Sum of AP = n/2 X (a + L)
=8/2 X (17 + 3)
= 4 X 20
= 80
No of trees = 80
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