Question

which terms of the series 711+15+...... is 403?

Answer 1

Actually after thinking very hard I could figure out that your series is :

7 , 11 , 15 , ................................. 403

This is an AP or Arithmetic Progression .

Woah it took me 20 minutes to understand that anyways :

We take first term as a

The common difference is d.

a = 7

d = 11 - 7 = 4

  or , 15 - 11 = 4

d = 4

Let 403 be the n th term .

We know that n th term of an AP is a + ( n - 1 ) d

                                                     ==> a + ( n - 1 ) d = 403

                                                     ==> 7 + ( n - 1 ) 4 = 403

                                                     ==> (n - 1) 4 = 403 - 7

                                                     ==> (n - 1)4 = 396

                                                     ==> (n - 1) = 396 / 4

                                                     ==> n - 1 = 99

                                                     ==> n = 99 + 1

                                                     ==> n = 100

The n th term is 403 .

100 th term is 403 .

The answer to your question is 100

Hope it helps you :-)

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