In 2023, the population in Singapore was 5 920 000, correct to the nearest ten thousand. The population increased by 4% from 2020 to 2023. Calculate the population in Singapore in 2020, giving your answer correct to the nearest ten thousand.

1. Identify the reverse percentage relationship

Since the population increased by $4\%$ from 2020 to 2023,

$\text{2023 population} = 104\% \text{ of 2020 population}.$

2. Calculate the original population and round appropriately

Let the population in 2020 be $P$.

$1.04P = 5\,920\,000$

$P = \frac{5\,920\,000}{1.04} = 5\,692\,307.692\ldots$

Correct to the nearest ten thousand,

$P = 5\,690\,000.$