A set of numbers has the property that for any number t in the set,t+3 is in the set. If -1 is in the set, which of the following must also be in the set?
I. 2
II. 5
III. 7
Choose the correct option:
A) II only  B) I only  C) I,II only  D) II,III only  E) III only
question is asking for must be there elements.   According to the question if t is there t+3 must be there.   if -1 is the starting element the sequence is as follows.   S ={-1,2,5,8,11....}   if -1 is not the starting element the sequence is as follows   S = {...-4,-1,2,5,8,11...}   By observing the above two sequences we can say that 2,5 must be there in set S.   Answer : I,II only
<result>C</result>
A set of numbers has the property that for any number t in the set,t+3 is in the set. If -1 is in the set, which of the following must also be in the set?
I. 2
II. 5
III. 7