Question

Find the sum of all numbers from 50 to 350 which are divisible by 4. Also find 15th term.

Answer 1

the sum of all numbers from 50to350 which are divisible by 4 is. 15000 and the 15th term is. 108

Answer 2

Answer:

The sum of these terms is 15000 and the 15th term is 108.

Step-by-step explanation:

It is given that the sum of all numbers from 50 to 350 which are divisible by 4.

52, 56, 60, ....,348.

Here first term is 52 and common difference is 4.

The nth term of series is

$a_n=a+(n-1)d$

$348=52+(n-1)4$

$348-52=(n-1)4$

$296=(n-1)4$

$74=(n-1)$

$n=75$

The sum of n terms of an AP is

$S_n=\frac{n}{2}[2a+(n-1)d]$

$S_{75}=\frac{75}{2}[2(52)+(75-1)4]=15000$

The sum of these terms is 15000.

The 15th term of AP is

$a_{15}=52+(15-1)4=108$

Therefore the sum of these terms is 15000 and the 15th term is 108.