Find the average speed.

Question

Two points, L and N, are 160m apart. M lies on the straight line joining L and N. An object from L to M travels at an average speed of 10m/s in 6 seconds and then from M to N at an average speed of 25m/s. Find the average speed of the object for its entire journey from L to N.

The answer to the question is 16m/s but I cant seem to get it, Help here would be nice :) .

Answer 1

Distance = (Rate)(Time)

Distance from L to M = (10m/sec)(6sec) = 60 m

Distance from M to N = 160 - 60 = 100 = (25)T (T is the time it takes to go from M to N)

So, T = 4 sec

Average speed for the entire trip = (Total Distance) / (Total Time) = 160 / (6+4) = 16 m/sec