Question 14
A rugby fan in Perth (Australia) plans to watch a live match played in New Zealand next winter. The time zone for Perth is UTC +8. The time zone for New Zealand is UTC +13 in winter and UTC +12 in summer.
If the match is played at 6:30 pm New Zealand time, what time will the match be viewed in Perth?
That’s it. Step through the hints below to see why. In 2022, 72.2% of Queensland students chose (A).
Not quite. One way to get 2:30 pm is to use UTC +12, which the question gives for summer. The match is next winter, and the question puts winter at UTC +13, so the gap is 5 hours, not 4. In 2022, 10.0% of Queensland students chose (B). If you used New Zealand’s real offsets, you are right about the real world. The note in the solution explains.
Not quite. One way to get 10:30 pm is to use the summer offset, a 4-hour gap, and then count forward. Perth is west of New Zealand, so its clocks read earlier, and the match is in winter. In 2022, 3.9% of Queensland students chose (C).
Not quite. The 5-hour gap is right, but it goes the wrong way. One way to get 11:30 pm is to add the 5 hours. Perth is west of New Zealand, so Perth’s clock is 5 hours behind. In 2022, 13.1% of Queensland students chose (D).
The strip shows every time zone’s clock at the moment the match starts. Each option comes from two choices: which New Zealand offset, and which way to count.
This is option (A). The question puts New Zealand on UTC +13 in winter, 5 hours ahead of Perth, so count back 5 hours. The strip agrees: Perth’s column reads 1:30 pm.
This is option (B). UTC +12 is the offset the question gives for summer, and this match is in winter.
This is option (C), two slips at once: the summer offset, then counting forward. The strip shows Perth’s clock reading , earlier than New Zealand, never later.
This is option (D). The 5-hour gap is right, but counting forward puts Perth ahead of New Zealand. The strip shows Perth reading , because it is further west.
The match is next winter. Take the winter offset straight from the question:
$$\text{NZ winter}=\text{UTC}+13$$
Perth stays on UTC +8 all year. The question gives you two New Zealand offsets, so you have to pick the one for the season it names.
Subtract the offsets to find the gap.
$$13-8=5\text{ hours}$$
The bigger offset is further east, and further east is ahead. New Zealand is ahead, so Perth is 5 hours behind.
Count back 5 hours from the New Zealand start time.
$$\text{6:30 pm}-5\text{ h}=\text{1:30 pm}$$
Check the direction: an evening match in New Zealand should be an afternoon match in Perth. Any answer later than 6:30 pm has counted the wrong way.
$$\begin{aligned}\text{gap}&=13-8=5\text{ hours}\\\text{Perth time}&=\text{6:30 pm}-5\text{ h}\\&=\text{1:30 pm}\end{aligned}$$
Use the winter offset from the question, find the gap, and count back because Perth is further west.
Only mark this done when you could do it without help. Reading the solution does not count.
Question wording is from the 2022 QCAA General Mathematics external assessment, © State of Queensland (QCAA) 2022, licensed under CC BY 4.0, and has been adapted. Tangent Tuition is not affiliated with the QCAA.
Spot a mistake on this page? Report it