Rationale
27 and 35 can be written in the blanks to achieve a constant difference.
To determine the two missing numbers in the sequence, we need to find a common difference that, when applied to the provided numbers, allows for a consistent interval between each consecutive pair. The difference must remain equal when moving from 19 to the first blank, then to the second blank, and finally to 43.
A) 25, 31
If we fill the blanks with 25 and 31, the differences are 25 - 19 = 6 and 31 - 25 = 6, but 43 - 31 = 12. This results in varying differences between consecutive numbers, thus failing to maintain a constant difference throughout.
B) 26, 36
Using 26 and 36, the differences are 26 - 19 = 7 and 36 - 26 = 10, while 43 - 36 = 7. Here, the differences are inconsistent, as the gap between 19 and 26 does not match the gaps after 36.
C) 27, 35
Filling the blanks with 27 and 35 gives us a uniform difference: 27 - 19 = 8, 35 - 27 = 8, and 43 - 35 = 8. Thus, all consecutive pairs maintain a constant difference of 8, making this the correct choice.
D) 28, 37
With 28 and 37, the differences are 28 - 19 = 9 and 37 - 28 = 9, but 43 - 37 = 6. This inconsistency in differences fails to satisfy the requirement for a constant difference across the entire sequence.
Conclusion
To achieve a constant difference in the sequence starting with 19 and ending with 43, the numbers 27 and 35 must be inserted. This selection ensures that the difference between each pair of consecutive numbers remains the same, specifically 8, illustrating the necessity for uniformity in such sequences. Other options do not provide the required consistency in differences, confirming the validity of option C.