Question

Could someone pls tell me why did they substitute t = 3 hrs instead of t = 1500 hrs in part c)?

Answer 1

See explanation.

Explanation:

They used `t=3` because, as it is said in point b the variable `t` is time after noon (in other words the variable `t` shows how many hours passed between the noon and the time for which the distance is calculated.)

In point `c` they are calculating the distance between the ships at 1500 hours, so `t` is:

`t=15.00-12.00=3`