Question

If 73is nth term of the airthematic progression 3,8,13,18,.... then n is

a) 13 b)14 c)15 d)16​

Answer 1

Answer: c) 15

Explanation:

3, 8, 13, 18, ... - the arithematic progression an=73 n=?

Difference of an arithmetic progression: d=a₂-a₁.

a₁=3 a₂=8

Hence,

d=8-3

d=5

Nth element of an arithmetic progression

`\boxed {a_n=a_1+(n-1)*d}`

`73=3+(n-1)*5\\73=3+5n-5\\73=5n-2\\73+2-2=5n-2\\75=5n\\`

Divide both sides of the equation by 5:

`15=n`

Answer 2

Explanation: