Question

Imp Question ❓
On the world environment day tree plantation programme was arranged on a land which is triangular in shape. Trees are planted such that in the first row there is one tree, in the second row there are two trees, in the third row three trees and so on. Find total number of trees in the 25 rows.​

Answer 1

Step-by-step explanation:

Given:On the world environment day tree plantation programme was arranged on a land which is triangular in shape. Trees are planted such that in the first row there is one tree, in the second row there are two trees, in the third row three trees and so on.

To find:

Find total number of trees in the 25 rows.

Solution:

First row: 1 tree

Second row : 2 trees

.

.

.

Twenty fifth row: 25 trees

To find :1+2+3+4+...+25

Sum of natural numbers up to 25,apply

sum of n terms

$S_n = \frac{n(n + 1)}{2}$

Here

n=25

$S_{25} = \frac{25 (25 + 1)}{2} \\ \\ S_{25} = \frac{25 \times 26}{2} \\ \\ S_{25} = 25 \times 13 \\ \\\bold{\green{S_{25} = 325}}$

Final answer:

Total 325 trees were planted.

Hope it helps you.

Answer 2

Answer:

$\underline{\pink{\ddot{\Rohithkumar.R.mathdude}}}$

☆Given :-

▪First we should write the given in the question .

▪Let,

▪Total number of rows =25

▪Number of trees in the first row = 1.

▪Number of trees in the second row is =2

▪Number of trees in third row = 3..

▪And also we can write as ,

▪Total numbers of trees as,

1+2+3+....+25rows.

☆To prove: -

▪Total number of trees in 25th rows.

☆Proof:-

▪In this question we should use the formula is

Sn= n/2 (2a+(n-1)d)

Lets take ,

a=1,

d= 1

n=25.

☆Next apply to the formula: -

S25=25/2(2a+(25-1)d)

S25= 25/2 (2 (1)+24 (1))

= 25/2 (2+24)

=25/2(26)

= 25×13

=325.

☆☆Therefore the total number of trees in 25 rows is 325.

☆Hope it helps u mate.

☆Thank you.