Fuel price ratio.

[Mohit_C]

Hi,

I have a question from an old question bank which no longer exist in recent question banks but here is the question anyways.

The flight crew of a turbojet aeroplane prepares a flight
using the following data:
- Flight leg distance: 3 500 NM
- Flight level FL 310, true airspeed: 450 kt
- Headwind component at this level: 55 kt
- Initially planned take-off mass (without extra fuel on
board): 180 000 kg
- Fuel price: 0.30 $/l at departure
The commander may carry a fuel quantity of 8 000 kg in
addition to that which is necessary.
For this fuel transport operation to be cost effective, the
maximum fuel price at arrival must be:
A 0.26 $/l
B 0.28 $/l
C 0.33 $/l
D 0.27 $/l

There is an annex attached to it but I think it's not needed. Now the ANSWER is supposed to be D however it doesn't make sense. In the annex it is mentioned that "fuel price ratio is the depature fuel price divided by the destination fuel price". In the annex the fuel price ratio doesn't exceed 0.99 on the y-axis.

Now using a bit of logic here, if the fuel is more expensive at the depature than at the destination it's no point in filling up more fuel. My teacher argues that perhaps the fuel price relationship in the annex is supposed to be: destination fuel price divided by departure fuel price. We can't seem to agree on that. Using the annex fuel price ratio definition provided, all other question regarding fuel price ratio seem correct. I would argue that the CORRECT ANSWER is supposed to be C.

Any ideas?

Thanks.