The following data relate to the marks of $\displaystyle 48$ students in Statistics:$\displaystyle 56$ $\displaystyle 10$ $\displaystyle 58$ $\displaystyle 38$ $\displaystyle 21$ $\displaystyle 43$ $\displaystyle 12$ \displaystyle 22<span class="katex-error" title="ParseError: KaTeX parse error: Can&#x27;t use function &#x27;' in math mode at position 3: 48\displaystyle ̲51$\displaystyle$39$\displaystyle$24\displaystyle …" style="color:#cc0000">48 $\displaystyle 51$ $\displaystyle 39$ $\displaystyle 24$ $\displaystyle 17$ $\displaystyle 36$ $\displaystyle 19</span>48$ $\displaystyle 36$ $\displaystyle 15$ $\displaystyle 33$ $\displaystyle 30$ $\displaystyle 62$ $\displaystyle 57$ \displaystyle 17<span class="katex-error" title="ParseError: KaTeX parse error: Can&#x27;t use function &#x27;' in math mode at position 2: 5\displaystyle ̲17$\displaystyle$45$\displaystyle$46\displaystyle …" style="color:#cc0000">5 $\displaystyle 17$ $\displaystyle 45$ $\displaystyle 46$ $\displaystyle 43$ $\displaystyle 55$ $\displaystyle 57$ $\displaystyle 38</span>43$ $\displaystyle 28$ $\displaystyle 32$ $\displaystyle 35$ $\displaystyle 54$ $\displaystyle 27$ $\displaystyle 17$ $\displaystyle 16$$\displaystyle 11$ $\displaystyle 43$ $\displaystyle 45$ $\displaystyle 2$ $\displaystyle 16$ $\displaystyle 46$ $\displaystyle 28$ $\displaystyle 45$What are the frequency densities for the class intervals $\displaystyle 20-30, 30-40, 40-50, 50-59$?