$80.0,80.5,81.0,81.5,82$
$M P E=\frac{1}{n} \sum\left(\frac{x-\bar{x}}{x}\right) \times 100 \%$ $...(1)$
The mean value of the errors is calculated as,
Mean of the errors $=\frac{80+80.5+81+81.5+82}{5}$
$=81$
$x$ | $x-\bar{x}$ | $\frac{x-\bar{x}}{x}$ |
$80.0$ | $1.0$ | $0.0125$ |
$80.5$ | $0.5$ | $0.0062$ |
$81.0$ | $0$ | $0$ |
$81.5$ | $0.5$ | $0.0061$ |
$82.0$ | $1.0$ | $0.122$ |
Sum$=0.037$ |
Substituting the values in equation $(1),$ we get
$M P E=\frac{1}{5} \times(0.037) \times 100 \%$
$=0.74 \%$