7 The continuous random variable \(X\) has probability density function
\(f ( x ) = \begin{cases} k x ^ { n } & 0 \leqslant x \leqslant 1 ,
0 & \text { otherwise, } \end{cases}\)
where \(k\) is a constant and \(n\) is a parameter whose value is positive. It is given that the median of \(X\) is 0.8816 correct to 4 decimal places. Ten independent observations of \(X\) are obtained. Find the expected number of observations that are less than 0.8 .