4 The runs scored by a cricketer in 11 innings during the 2006 season were as follows. $$\begin{array} { l l l l l l l l l l l } 47 & 63 & 0 & 28 & 40 & 51 & a & 77 & 0 & 13 & 35 \end{array}$$ The exact value of \(a\) was unknown but it was greater than 100 .

1. Calculate the median and the interquartile range of these 11 values.
2. Give a reason why, for these 11 values:
   1. the mode is not an appropriate measure of average;
   2. the range is not an appropriate measure of spread.