There are a couple of these in the Exam system …. this one only requires a temperature correction …. MOCA 8500ft is QNH …

Temperature correction …. 4% per 10Ί deviation from ISA

ISA at FL85 = -2Ί C, so temperature condition is ‘ISA-18 ΊC’

Correction 7.2% from 8500ft to DATUM (4000ft).

Datum in this instance is our met station at 4000ft

7.2% x 4500 = 324ft

Is it plus or minus 324ft … high to low careful go … temp is low …. +324ft

Answer 8824ft.

So - actual answer we will take 8800ft ..... the closest .... which you could argue is a little inconsistent, but never mind!!!