The strength of a school increases and decreases in every

The strength of a school increases and decreases in every alternate year by 10%. It started with increase in 2000. Then the strength of the school in 2003 as compared to that in 2000 was

1. increased by 8.9%
2. decreased by 8.9%
3. increased by 9.8%
4. decreased by 9.8%

Using Rule 4,
Increase in first year = 10%
Decrease in 2nd year = 10%
Effective result

=		10 - 10 -	10 × 10		% = –1%
			100

Increase in 3rd year = 10%
∴ Effective result

=		10 - 1 -	10 × 1		%
			100

= (9 – 0.1)% = 8.9% (increase)