The mean and variance of 10 observations are 9 and 34.2,...

Given 10 observations with mean = 9 and variance = 34.2.
Eight known values: 2, 3, 5, 10, 11, 13, 15, 21.
Sum of all 10: $\sum x_i = 90$.
Sum of 8 known: 80. So the two unknowns sum to 10.
From variance: $\sum x_i^2 = 10(34.2 + 81) = 1152$.
Sum of squares of 8 known: 1094. So unknown squares sum to 58.
With $x_9 + x_{10} = 10$ and $x_9^2 + x_{10}^2 = 58$: we get $x_9 x_{10} = 21$, giving roots $t^2 - 10t + 21 = 0$, so the unknowns are 3 and 7.
All 10 sorted: 2, 3, 3, 5, 7, 7, 10, 11, 13, 15, 21.
Median = $\frac{7+10}{2} = 8.5$.
Mean deviation = $\frac{1}{10}(6.5 + 5.5 + 5.5 + 3.5 + 1.5$ $+ 1.5 + 2.5 + 4.5 + 6.5 + 12.5)$ $= \frac{50}{10} = 5$