The ratio 45 minutes to 3 hours 45 minutes can be written in the form 1 : n - OCR - GCSE Maths - Question 3 - 2020 - Paper 1

To find the value of n, first convert both times to a common unit, such as minutes:

1. Convert 3 hours 45 minutes to minutes:

   $$3 \text{ hours } = 3 \times 60 = 180 \text{ minutes}$$ $$3\text{ hours } 45 \text{ minutes } = 180 + 45 = 225 \text{ minutes}$$

2. Now we have the ratio of 45 minutes to 225 minutes:

   $$\text{Ratio} = \frac{45}{225}$$

3. Simplifying this ratio gives us:

   $$\frac{45 \div 45}{225 \div 45} = \frac{1}{5}$$

Thus, we can express the ratio in the form 1 : n, where n = 5.