a hare and a tortoise have a race along a circle of 100 yards diameter . the tortoise goes in one direction and the hare in the other . the hare starts after the tortoise has covered 1 / 5 of its distance and that too leisurely . the hare and tortoise meet when the hare has covered only 1 / 8 of the distance . by what factor should the hare increase its speed so as to tie the race ?