A person, with his ear to the ground, sees a huge stone strike the concrete pavement. A moment later two sounds are heard from the impact: one travels in the air and the other in the concrete, and they are 1.7 s apart. How far away did the impact occur?

1 answer

You did not give me the speed of sound in air and in concrete
call air va and concrete vc
d = va t
d = vc (t-1.7)
so
va t = vc t - 1.7 vc
t (vc-va) = 1.7 vc
solve for t
then
d = va t