A frequency distribution: $0$-$10$: $5$, $10$-$20$: $9$, $20$-$30$: $14$, $30$-$40$: $10$, $40$-$50$: $2$.…
A frequency distribution: $0$-$10$: $5$, $10$-$20$: $9$, $20$-$30$: $14$, $30$-$40$: $10$, $40$-$50$: $2$. How many observations are at least $20$ but less than $40$?
$14$
$20$
$24$
$26$
Solution
Add frequencies of classes $20$-$30$ and $30$-$40$: $14+10 = 24$.