SOLUTION: A Gardener is making a trapezoidal planting, with 32 plants in the front row, 26 in the second row, 20 in the third row and so on. If the pattern is consistent, how many plants wil

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Question 890677: A Gardener is making a trapezoidal planting, with 32 plants in the front row, 26 in the second row, 20 in the third row and so on. If the pattern is consistent, how many plants will there be altogether if there are two plants in the last row?
Found 2 solutions by Lapric, richwmiller:
Answer by Lapric(19) About Me  (Show Source):
You can put this solution on YOUR website!
A Gardener is making a trapezoidal planting, with 32 plants in the front row, 26 in the second row, 20 in the third row and so on. If the pattern is consistent, how many plants will there be altogether if there are two plants in the last row?
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So the pattern is -6. 32-6=26. 26-6=20. 20-6=14. 14-6=8. 8-6=2.
32+26+20+14+8+2=102.
The gardener has 6 rows and 102 plants.

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
S = ½(a1 + an)n
S = ½(a1 + an)n
an = a1 + (n - 1)d
an = 32 -6(n-1)
2 = 32 -6n + 6
6n=36
n=6
S = ½(32 + 2)6
S=1/2*34*6
S=17*6=102