Question

ARITHMETIC PROGRESSIONS CLASS 10
In a garden there are 30 mango trees in the first row, 27 in the second row, 24 in the third row and so on .There are 6 trees in the last row. How many rows are there of mango trees.

Answer 1

a=30 and d=3 n=6

tn=a+(n-1)d

tn=30+(6-1)3

tn=30+5×3

tn=30+15

tn =45