Tourists were on a hiking trip for three days. on the first day, they hiked 1/8 of the trail. on the second day they hiked 4/7 of the remaining trail. on the third day they hiked 1/3 of the remaining trail and the last 8 km. how many km is the whole trail?

Let x = the length (km) of the whole trail.

1st day:
(1/8)x = 0.125x traveled.
Remaining amount = (1 - 0.125)x = 0.875x

2nd day:
(4/7) of 0.875x = 0.5x traveled.
Remaining amount = (1 - 0.5)x = 0.5x

3rd day:
(1/3) of 0.5x = 0.1667x traveled + 8 km

The total fractional parts traveled is
0.125x + 0.5x + 0.1667x = 0.7917x

The remaining fractional shares is (1 - 0.7917)x = 0.2083x.
This is equal to the 8 km traveled, therefore
0.2083x = 8
x = 8/0.2083 = 38.406 km

38.4 km (nearest tenth)