Question

Find the number of terms in the A.P.: 18, `15 1/2, 13, ...., -47.`

Answer 1

We have been given an A.P

18, `15 1/2`, 13, .... -47.

Here, a = 18, d = `15 1/2 - 18 = -5/2` , `a_n = -47`

We will find n using

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

Plugging the values in the formula we get:

`-47 = 18 + (n - 1) (-5/2)`

`-47 = 18 - 5/2n + 5/2`

n = 27

Therefore, there are 27 terms in an A.P