ATPL-JAR impossible question

[number]

Hello,


I'm dealing with the ATPL-JAR questionare and I don't succeed to answer this question:

At an altitude of 25000ft, the t° is -40C° and pressure is 375mb. The interval corresponding to 1 mb decrease in pressure is:...?

I'd like to know if there's a special formula to solve this question.
Thank you!!

[Xacto]

Hello Number
The formula you need is 96 times T/p where T is the temperature in degrees Kelvin and p is the pressure in millibars.
Thus in your example 96((273-40)/375) = 59.648.

Regards,

Xacto.