Question

There were runners to start a race. In the first half of the race, of them dropped out. In the second half of the race, of the remaining runners dropped out. How many runners finished the race?

Answer 1

Since we haven't exact input data, then we consider next example:

Let
there were 80 runners at start.
After first half 1/5 of runners dropped out.
=> 4/5 remained
After second half 1/4 of remained runners dropped out.
=> 3/4 remained

So if n is number of runners who finished the race,
then n=80*(4/5)*(3/4)=48