Answer
$\Delta t=4.0s$
The time interval is about 4.0 seconds
Work Step by Step
From the graph, we know $\Delta t=8.0s$ when $\beta =0$. Now we can use the time dilation equation with the given velocity to solve for the time interval.
$\Delta t=\Delta t_0 / \sqrt{1-(v/c)^2 }$
$\Delta t=8.0s / \sqrt{1-(0.98c/c)^2 }$
$\Delta t=4.0s$
The time interval is about 4.0 seconds.
