The line that divides the box of the box-and-whisker plot is located above 55 on the number line. This represents the median of the data set, not the midrange of the data set.

The box-and-whisker plot shows the greatest value of the data set to be 145 and the least value to be 25. Add these values together and divide by 2 to find the midrange: $\displaystyle\frac{{{145}+{25}}}{{2}}=\frac{{170}}{{2}}={85}\usepackage{cmbright}\Huge\$ . So it is not true that the midrange is 55.