In a 5000 m race, the athletes run 12 1/2 laps; each lap is 400 m. kara runs the race at a constant pace and finishes in 17.9 min. hannah runs the race in a blistering 15.3 min, so fast that she actually passes kara during the race. how many laps has hannah run when she passes kara?

No. of laps of Hannah are 7 (approx).

Solution:

According to the question:

The total distance to be covered, D = 5000 m

The distance for each lap, x = 400 m

Time taken by Kara,

Time taken by Hannah,

Now, the speed of Kara and Hannah can be calculated respectively as:

Time taken in each lap is given by:

t = 500 s

So, Distance covered by Hannah in 't' sec is given by:

No. of laps taken by Hannah when she passes Kara:

≈ 7 laps

a and b sometimes have a positive value