Ответ:

1) 2/15 < n/15 < 1/3

2/15 < n/15 < 5/15

n = 3, 4

2) 11/16 < n/24 <= 7/8

33/48 < 2n/48 <= 42/48

n = 17, 18, 19, 20, 21

3) 5/12 < n/12 < 2/3

5/12 < n/12 < 8/12

n = 6, 7

4) 1/16 <= n/24 < 1/4

3/48 <= 2n/48 < 12/48

n = 2, 3, 4, 5