A particle moves in a straight line so that its speed is constant for a mile and then changes abruptly for the next mile and is constant for that mile, then changes again, and so on. It moves so that its speed for a given mile varies inversely as the total integral number of miles previously traveled. If the second mile is traversed in 2 hours, how long does it take to travel the *n*th mile?

Make a chart.

Now, for that

*n*th mile,*d*= 1 =*r*_{n}*t*.So 1 = | 1 | · t, so t = 2(n – 1). |

2(n – 1) |