Given: The sum of a sequence of six consecutive positive integers is Z. The sum of terms in a different sequence of five consecutive integers is Z − 5.
Asked: If the greatest term of the five-number sequence is 40, what is the difference between the median term of the five-number sequence and the least term of the six-number sequence?
Let the six consecutive positive integers be
a-2,a-1,a,a+1,a+2,a+3
The sum of a sequence of six consecutive positive integers is Z
6a + 3 = Z
The sum of terms in a different sequence of five consecutive integers is Z − 5.
Let the sequence be
b-2,b-1,b,b+1,b+2
The sum of terms in a different sequence of five consecutive integers = 5b = Z − 5
Z = 5b + 5 = 6a + 3
The greatest term of the five-number sequence is 40
b+2 = 40; b = 38
Z = 5b + 5 = 195 = 6a + 3
a = 32
The difference between the median term of the five-number sequence and the least term of the six-number sequence = |b-(a-2)| = |38 - 30| = 8
IMO C