Answer:
20%
Step-by-step explanation:
Let x represent the initial value of the stock at the beginning of 2006. And y the value at the end of 2006.
When it went up by 25% in 2006;
y = x + 25% of x = x + 0.25x = 1.25x
For the value to go back to the original price, it has to decrease from y to x;
y = 1.25x
The percentage decrease from y to x is;
= (y-x)/y × 100%
Substituting the values;
= (1.25x -x)/1.25x × 100%
= 0.25x/1.25x × 100%
= 0.2 × 100%
= 20%
Therefore, it will have to go down 20%