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.
Answers
Answered by
0
Answer:
30,27,24,21,18,15 =135
Answered by
1
a1=30.
a2=27
Therefore d= a2 - a1
=27-30
= -3
an = 6
an = a+(n-1)d
6. = 30+(n-1)-3
6. = 30 - 3n +3
6 = 33 - 3n
6-33 = -3n
-27. = -3n
-27/-3 = n
+9. =n
Therefore there are 9 rows of mango trees.
Hope it helps you.
Similar questions