Take a Walk Answer

Number each girl from 1 to 15. Arrange girls 1 - 14 around a circle, consecutively, in a clockwise direction. Put girl 15 in the center.

On day one, group them like this: 1-8-15, 2-5-13, 3-7-12, 4-6-14, 9-10-11.

On each succeeding day, rotate the configuration clockwise by 2 girls. Keep girl 15 in the center. So on day two, they would be grouped like this: 3-10-15, 4-7-1, 5-9-14, 6-8-2, 11-12-13. Continue in the same manner for days 3 through 7.