Consider the following changes in the series:
The series alternates between increasing and decreasing, and the differences increase in magnitude by 2 each time (2, 0, 2, 4, 6).
Thus, the next change should be an increase by 8:
\[ 1 + 8 = 9 \]
The correct answer is (c) 9.
Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?