Question

$If \: \: 73 \: \: is \: \: {then}^{th} \: \: term \: \: of \: \: the \: \: ap \: \: 3, \: \: 8, \: \: 13, \: \: 18 \: \: then \: \: n \: \: is$

Please don't give unnecessary answer's

Answer 1

Given: nth term of an AP 3, 8, 13,... is 73

To find: Value of n

Solution:

We know that the nth term of an AP is given by,

• an = a + (n - 1)d

Here, a = first term, d = common difference, an = nth term and n is number of terms.

In the given AP,

• a = 3

• d = 8 - 3 = 5

Substituting the know values in the general from of AP.

⇒   an = a + (n - 1)d

⇒   73 = 3 + (n - 1)(5)

⇒   73 - 3 = 5n - 5

⇒   70 = 5n - 5

⇒   70 + 5 = 5n

⇒   75 = 5n

⇒   75/5 = n

⇒   15 = n

So the required value of n is 15.