Note that
25 + 36 = 61.
The partial sums of 61 are
1, 3, 6, 10, 15, 21, 28, 36, 45, 55.
These numbers arise in partial sums of 61.
4 = 1 + 3
6 is a partial sum
11 = 1 +10
31 = 10 + 21
36 is a partial sum
41 cannot be obtained from partial sums.
56 = 28 + 28
61 is a partial sum
Test the given answers.
A) 11,31,61 qualify as partial sums. It is correct.
B) 11,31,61 qualify as partial sums. It is correct.
C) 11 and 61 qualify as partial sums, but 41 does not. It is incorrect.
D) 36,56,61 qualify as partial sums. It is correct.
Answer:
C) is incorrect.
