Sequence: 4, 9, 19, 39, ?

The next number in the sequence 4, 9, 19, 39, is 79. To understand how this sequence progresses, we can analyze the pattern in the differences between consecutive terms.

Starting with the first two terms, the difference between 9 and 4 is 5. The difference between 19 and 9 is 10, and the difference between 39 and 19 is 20. We can observe that the differences themselves form a sequence: 5, 10, and 20. The pattern in these differences shows that each difference doubles the previous one, suggesting a consistent growth in the increments.

Continuing this pattern, the next difference should be double the last difference of 20, which gives us 40. Adding this difference of 40 to the last term in the original sequence, 39, results in 79. Thus, following the established pattern in the sequence leads us to the conclusion that the next term is indeed 79. Understanding such sequences is crucial in competitive exams, as they often test logical reasoning and pattern recognition skills.