Jawaban:

(a) To find the exchange rate between Singapore dollars and Australian dollars in AUD/SGD, we can use the given exchange rates:

1 SGD = 0.816 USD

1 AUD = 1.073 USD

To convert from SGD to AUD, we can first convert SGD to USD, and then convert USD to AUD:

1 SGD = 0.816 USD

1 SGD/0.816 USD = 1.22549019608 SGD/USD (using the reciprocal of 0.816)

1 AUD = 1.073 USD

1.073 USD/1 AUD = 0.93121440823 AUD/USD (using the reciprocal of 1.073)

Now, to get the exchange rate between SGD and AUD, we can divide the AUD/USD exchange rate by the SGD/USD exchange rate:

0.93121440823 AUD/USD ÷ 1.22549019608 SGD/USD ≈ 0.759 AUD/SGD

Therefore, the exchange rate between Singapore dollars and Australian dollars in AUD/SGD is approximately 0.759, correct to 3 decimal places.

(b) To find the required amount of Singapore dollars to remit 25,000 AUD, we can use the exchange rate we found in part (a):

1 AUD = 0.759 SGD (approximately)

Therefore, 25,000 AUD is equivalent to:

25,000 AUD × 0.759 SGD/AUD ≈ 18,975 SGD

Rounding to the nearest dollar, the required amount of Singapore dollars is 18,975 SGD.