Reference frame $S^{\prime}$ passes reference frame $S$ with a certain velocity as in Fig. $37-9$ . Events 1 and 2 are to have a certain spatial separation $\Delta x^{\prime}$ according to the $S^{\prime}$ observer. However, their temporal separation $\Delta t^{\prime}$ according to that observer has not been set yet. Figure $37-30$ gives their spatial separation $\Delta x$ according to the $S$ observer as a function of $\Delta t^{\prime}$ for a range of $\Delta t^{\prime}$ values. The vertical axis scale is set by $\Delta x_{a}=10.0 \mathrm{m} .$ What is $\Delta x^{\prime \prime} ?$