Answer:
The value is
![v = 0.996c](https://img.qammunity.org/2021/formulas/physics/college/vnde1w4cpevljjvyn42pifltbm6snc8eok.png)
Step-by-step explanation:
From the question we are that
The number by which the clock on the spacecraft should be slower than that on the earth is
![N = 10.7](https://img.qammunity.org/2021/formulas/physics/college/9wdj1v10qp7j613fp1vr7m7pw25uv7hzyg.png)
Generally from the time dilation relation given by Albert Einstein we have that
![\Delta t _1 = \frac{ \Delta t_2 }{ \sqrt{1 - (v^2)/(c^2 ) } }](https://img.qammunity.org/2021/formulas/physics/college/w4k19njf6bed50u67unbnrnkj42dnl1os6.png)
Here
is the time on earth
is the time on the spacecraft
v is the speed of the spacecraft
c is the speed of light with value
![c= 3.0*10^(8) \ m/s](https://img.qammunity.org/2021/formulas/physics/college/tekxrt9jxuiw4colheakj1nb3drmekwhgk.png)
So
![(v^2 )/(c^2) = 1 - (\Delta t_2 )/(\Delta t_1)](https://img.qammunity.org/2021/formulas/physics/college/5keekz8zmt59ktod38ew5fpppkstaby51z.png)
Given that
![\Delta t_1 = N \Delta t_2](https://img.qammunity.org/2021/formulas/physics/college/wcg3j4j1bv4jj4wetrgjs9p4h6clgpmh6i.png)
![\Delta t_1 = 10.7 \Delta t_2](https://img.qammunity.org/2021/formulas/physics/college/ud4zl6fzkw5uwmek5p59irv8jrjw072j01.png)
So
![v = c \sqrt{ 1 - ( \Delta t_2 )/(10.7 \Delta t_2) }](https://img.qammunity.org/2021/formulas/physics/college/xxf0vk86xzy7x21oif5ixsgc47x1pqlr3k.png)
![v = 0.996c](https://img.qammunity.org/2021/formulas/physics/college/vnde1w4cpevljjvyn42pifltbm6snc8eok.png)