A scooter accelerates from rest for time $t _ { 1 }$ at constant rate $a _ { 1 }$ and then retards at constant rate $a _ { 2 }$ for time $t _ { 2 }$ and comes to rest. The correct value of $\frac { t _ { 1 } } { t _ { 2 } }$ will be :\\
(1) $\frac { a _ { 2 } } { a _ { 1 } }$\\
(2) $\frac { a _ { 1 } } { a _ { 2 } }$\\
(3) $\frac { a _ { 1 } + a _ { 2 } } { a _ { 1 } }$\\
(4) $\frac { a _ { 1 } + a _ { 2 } } { a _ { 2 } }$