1. The problem asks us to identify which ratios are equivalent to $1:20$. 2. Two ratios $a:b$ and $c:d$ are equivalent if their cross products are equal, i.e., $a \times d = b \times c$. 3. Let's check each ratio against $1:20$ by cross multiplication: - For $11:8$, check if $1 \times 8 = 20 \times 11$ which is $8 = 220$ (False). - For $2:50$, check if $1 \times 50 = 20 \times 2$ which is $50 = 40$ (False). - For $4:80$, check if $1 \times 80 = 20 \times 4$ which is $80 = 80$ (True). - For $3:60$, check if $1 \times 60 = 20 \times 3$ which is $60 = 60$ (True). 4. Therefore, the ratios equivalent to $1:20$ are $4:80$ and $3:60$. Final answer: $4:80$ and $3:60$ are equivalent to $1:20$.