An airline flight of 5 hours in the middle latitudes at an altitude of 12 km may result in an exposure of _____  µSv.
Directly picked from White and Pharoah:
"An airline flight of 5 hours in the middle latitudes at an altitude of 12 km may result in an exposure of about 25 µSv".
White and Pharoah's Oral  Radiology Principles and Interpretation 8th edition
25
50
250
100