The strength of a school increases and decreases by 15% every other year. If the increase started in 2012, what was the strength (correct to two decimal places, in %) of the school at the beginning of 2015 as compared to 2012?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. Increased by 12.41%.
Let the strength of the school in 2012 be 100.
⇒ Strength of school in 2013 after the increase of 15% = 100 × 115/100 = 115
⇒ Strength of school in 2014 after the decrease of 15% = 115 × 85/100 = 97.75
⇒ Strength of school at the beginning of 2015 after the increase of 15% = 97.75 × 115/100 = 112.41
The strength of the school at the beginning of 2015, as compared to that in 2012 increased by
= [(112.41 - 100)/100] × 100 = 12.41%