How to calculate ground speed using a map with a known scale and time? If an aircraft flies from point A to B for a distance of 8cm on a chart of 1:1,000,000 in 18 minutes, What’s the ground speed?

It’s a multiple choice question and the possible answers are in ratios.
(#45 in the image)




  A. $1:1,105,550$
  B. $1:1,250,000$
  C. $1:1,740,740$
  D. $1:1,074,740$


I can’t change the question but I can explain how it is related to aviation.  The question is from flight dispatcher module Air Navigation, where by in dispatching the aircraft we must know about places where aerodromes are located passing etc and so we learn about maps and charts.. am not off topic the question is 100% aviation related
If a plane traveled $8\ \mathsf{cm}$ on a map with a scale of $1:1\ \mathsf{million}$, then it traveled $8\ \mathsf{million\ cm}$ in the real-world.

$$8\ \mathsf{million\ cm} = 80,000\ \mathsf{meters} = 80\ \mathsf{km}$$

Convert 80 km in 18 minutes to a speed of kilometers per hour:

$$\frac{80\ \mathsf{km}}{18\ \mathsf{min}} \cdot \frac{60\ \mathsf{min}}{1\ \mathsf{hour}} = 266.6 \frac{\mathsf{km}}{\mathsf{hr}}$$

Groundspeed is traditionally expressed in knots:

$$266.6\ \mathsf{kph} \cdot \frac{0.54\ \mathsf{kts}}{1\ \mathsf{kph}} = 144\ \mathsf{kts}$$

To put this in perspective, 144 kts is a bit fast for a Cessna 172, unless it has a good tailwind, but not at all unreasonable for many small high-performance planes.



The answers to question #44 don't make sense.
The question is "The scale of the chart is...", but the possible answers are all KTS (knots).

The answers to #44 and #45 are clearly reversed.
However, the right answer of 144 kts, is not listed in the possible answers.

In general, I think that test is extremely poor quality.

Question #43 (movement of the earth around the sun) may not even be related to aviation.