If a rod of length 250cm is measured as 255cm long in error, what is the percentage error in the measurement?

A.
55 
B.
10 
C.
5 
D.
4 
E.
2
Correct Answer: Option E
Explanation
% error = (frac{text{Actual error}}{text{real value}}) x 100
= (frac{5}{250}) x 100
= 2%