Answer:
![t=1.25\,s](https://img.qammunity.org/2020/formulas/physics/high-school/rh3e0ms1pmnpuca02onkt6cx5d2pvwa6qe.png)
Step-by-step explanation:
In a thunderstorm the lightening is seen first then the roar of the lightening is heard because of the fact that speed of the light is much greater than the speed of the sound.
Given that:
Relation
![M=t* 5.6](https://img.qammunity.org/2020/formulas/physics/high-school/z6455d56qja0ktbtu8l6etdxb4unjppr7e.png)
M= 7 miles
t=?
where:
t= time in seconds
M= distance in miles
Now,
Putting the given values in the relation above
![7=t* 5.6](https://img.qammunity.org/2020/formulas/physics/high-school/e3jxkqd0r0vieep10lfsebwcxzyh8webd4.png)
![t=1.25\,s](https://img.qammunity.org/2020/formulas/physics/high-school/rh3e0ms1pmnpuca02onkt6cx5d2pvwa6qe.png)