Consider the sets Tn={n,n+1,n+2,n+3,n+4},
where n = 1, 2, 3,..., 96. How many of these sets contain 6 or any integral
multiple thereof (i.e., any one of the
numbers 6,
12, 18,...)?
(1) 80
(2) 81
(3) 82
(4) 83

Consider the
sets Tn
= {n, n + 1, n +2, n + 3, n + 4), where n = 1

T1: 1,2,3,4,5

T2: 2,3,4,5,6

T3: 3,4,5,6,7

etc.

means that every multiple of 6 will be
involved in 5 sets.