Answer
See below.
Work Step by Step
The mean of $n$ numbers is the sum of the numbers divided by $n$. The median of $n$ is the middle number of the numbers when they are in order (and the mean of the middle $2$ numbers if $n$ is even). The mode of $n$ numbers is the number or numbers that appear(s) most frequently.
Hence here the mean: $\frac{15+19+19+22+24+25+26+30+35+39+42}{11}=26.91$.
The median is the middle in the sequence $15, 19, 19,22,24,25, 26, 30, 35, 39, 42$, which is: $25$.
The mode is $19$.
