Any floating-point representation used in a computer can represent only certain real numbers exactly; all others must be approximated. If A′ is the stored value approximating the real value A, then the relative error, r, is expressed as
r = A - A′/A
Represent the decimal quantity +0.4 in the following floating-point format: exponent: biased, 4 bits; significand, 7 bits. What is the relative error?