College Algebra 7th Edition

$a_4 = \dfrac{24}{25}$
To find the fourth term, the value of the common ratio $r$ is needed. The value $r$ can be found by dividing the second term by the first term of the sequence. Thus, $r=\dfrac{a_2}{a} \\r=\dfrac{6}{15} \\r=\dfrac{2}{5}$ The fourth term can be found by multiplying the common ratio $r$ to the second term twice: $a_4 = a_2 \cdot r \cdot r \\a_4 = 6 \cdot \dfrac{2}{5} \cdot \dfrac{2}{5} \\a_4 = \dfrac{24}{25}$