A histogram has class intervals $20$-$30, 30$-$40, 40$-$50, 50$-$60$ with frequencies $8, 12, 6, 4$. What…
A histogram has class intervals $20$-$30, 30$-$40, 40$-$50, 50$-$60$ with frequencies $8, 12, 6, 4$. What fraction of total observations lies in $30$-$40$?