Question

Find the sum of all natural no. Between 200 and 1502 which are exactly divisible by 3

Answer 1

Answer:

Step-by-step explanation:

Using AP:

a=201 ; l=1500. d=3;

1500= 201+(n-1)3;

1500-201+3=3n;

1503-201=3n;

1302=3n;

n=434;

sum= 434/2(201+1500)

=217(1701)

=369117

Answer 2

Step-by-step explanation:

The natural no. between 200 to 1502 that are divisible by 3 are 201,204,207,.......,1500

THEN,

a = 201

d = 204 - 201 = 3

l = 1500

a + (n - 1) d = l

201 + (n - 1) 3 = 1500

3 (n - 1) = 1500 - 201

n - 1 = 1299/3

n = 433 + 1

n = 434

NOW,

Sn = n/2 (a + l)

Sn = 434/2 (201 + 1500)

Sn = 217 × 1701

Sn = 369117