Question

Which expression can be used to convert 80 US dollars (USD) to Australian dollars (AUD)?

1 USD = 1.0343 AUD
1 AUD = 0.9668 USD

A) 80 USD x (0.9668 USD / 1 AUD)
B) 80 USD x (1.0343 USD / 1 AUD)
C) 80 USD x (0.9668 AUD / 1 USD)
D) 80 USD x (1.0343 AUD / 1 USD)

(A is incorrect)

Answer 1

D) 80 USD x (1.0343 AUD / 1 USD)

Explanation:

The conversion rate that we need goes from 1 USD to the number of AUD. This means we need the first conversion rate, 1 USD = 1.0343 AUD.

Since we have 80 USD, we are going to multiply 80 by our conversion rate, 1.0343; this eliminates choices A and C.

We want to have our units as AUD when we're finished. This means that when we multiply, AUD must be on the top of the rate we're multiplying by; this means D is our answer.

Answer 2

The answer is D. The first thing to do is to check units. The unit for the answer should be AUD since we are converting USD to AUD, so only C and D work. 1 USD is equal to 1.0343 AUD, instead of the other way around (1USD=0.9668AUD), which means 80 USD should be multiplied by 1.0343 AUD/1USD, because AUD is cheaper and there should be more AUDthan USD after conversion.