Question

If the first term in an arithmetic sequence is 15 and the tenth term is 69. What is the fourth term in the sequence?

Answer 1

Hello,

$a_{0}=15$ first term
$a_{1}=15+r$ second term
$a_{2}=15+2r$  third term
...
$a_{9}=15+9r$ is the tenth term =69

15+9r=69
==>9r=69-15
==>r=54/9=6
$a_{3}=15+3r=15+18=33$