Question 8
Which statement is correct?
Not quite. The mean solar time on the prime meridian at Greenwich is GMT, and Greenwich sits at 0° longitude, nowhere near the equator. UTC is the modern world standard that took over from GMT. In 2025, 8.1% of Queensland students chose (A).
That’s it. Step through the hints below to see why. In 2025, 46.7% of Queensland students chose (B).
Not quite. The International Date Line runs roughly along 180° longitude. The prime meridian is 0°, on the opposite side of the Earth. In 2025, 29.5% of Queensland students chose (C).
Not quite. Only the zone on the west side of the line is ahead of GMT. Step east across the line and you land in a zone behind GMT, a whole day earlier. In 2025, 14.8% of Queensland students chose (D).
Pick a statement to test it on the map. Each one is about where something sits on the Earth.
(A) is false. Mean solar time is measured at Greenwich, on the prime meridian (orange), and that time is called GMT. The equator (blue rim) has no time standard of its own.
(B) is true. UTC, Coordinated Universal Time, is the standard the whole world sets its clocks by. Every zone around the rim is an offset from it. Queensland is UTC +10.
(C) is false. The prime meridian runs down from the pole and the date line runs up from it. They are 180° apart, on opposite sides of the Earth. Like every pair of meridians, they only come together at the poles.
(D) is false. The zone on the west side of the line (orange, +12) is ahead of GMT. The zone on the east side (blue, −12) is behind it. Same clock time, different day.
Keep the two names apart.
GMT, Greenwich Mean Time, is the mean solar time at Greenwich, on the prime meridian.
UTC, Coordinated Universal Time, is the time standard used around the world. It is kept by atomic clocks and matches GMT for everyday purposes, so zones are written as offsets like UTC +10.
That makes (B) true. (A) swaps Greenwich for the equator and GMT for UTC.
Place the two special meridians.
$$\text{prime meridian: }0^\circ\qquad\text{date line: about }180^\circ$$
They are half a turn apart, on opposite sides of the Earth. Apart from the poles, where every meridian meets, the date line never comes near the prime meridian, so (C) is false.
Look either side of the date line. Going east from Greenwich, the offsets climb to $+12$. Going west, they fall to $-12$. The two ends meet at the date line.
So one neighbour of the line is ahead of GMT and the other is behind it. “Each” zone being ahead fails, so (D) is false.
(A) False. Mean solar time at Greenwich, on the prime meridian, is GMT. The equator plays no part.
(B) True. UTC is the world’s time standard, and every time zone is an offset from it.
(C) False. The date line is at about 180°, the prime meridian at 0°. They are on opposite sides of the Earth.
(D) False. The zone just west of the line is ahead of GMT, and the zone just east of it is behind.
Only mark this done when you could do it without help. Reading the solution does not count.
Question wording is from the 2025 QCAA General Mathematics external assessment, © State of Queensland (QCAA) 2025, licensed under CC BY 4.0, and has been adapted. Tangent Tuition is not affiliated with the QCAA.
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