Express each of the following as a per cent :
`1 : 5`

Answer

To express the ratio \(1 : 5\) as a percentage, follow these steps:

### Step-by-Step Solution:

1. **Convert the Ratio to a Fraction**:
The ratio \(1 : 5\) can be expressed as a fraction:
\[ \frac{1}{5} \]

2. **Multiply the Fraction by 100**:
To convert the fraction to a percentage, multiply it by 100:
\[ \frac{1}{5} \times 100 \]

3. **Calculate the Value**:
Now, perform the multiplication:
\[ \frac{100}{5} = 20 \]

4. **Write the Result as a Percentage**:
The final result can be expressed as:
\[ 20\% \]

### Final Answer:
Thus, \(1 : 5\) expressed as a percentage is \(20\%\).

---