I have the RPL/PPL Study Guide Volume 2, "last revised November 2018", and it
seems like every row but the first in the answers for exercise no 7 on page 211
are wrong.

For example, given:

* 30 mins fixed reserve at cruise rate required
* Start up and taxi allowance of 8 litres
* Variable reserve of 10%
* Cruise fuel flow of 44 lph
* EET of 57 minutes

Then we should expect the trip fuel is 44 * 57 / 60 = 41.8 litres, and the fiel
required at startup is 41.8 * 1.1 + 8 + 44 * 0.5 = 76 litres, correct?

But the book says the startup fuel is 90.5 litres. It makes different errors
(plus or minus) in different rows; only the first appears to be correct.

Is this an error in the book, or have I misunderstood the calculation? :-/

Perhaps you missed that the fixed reserve is different in each question. At 30 minutes at cruise rate you get a different fixed reserve in each case.

Question 1
35 x 206 ÷ 60 = 120.2 litres = 31.8 gallons
120.2 x 1.1 +17.5 + 8 = 157.7 litres = 41.7 gallons

Question 2
55 x 133 ÷ 60 = 121.9 litres = 32.2 gallons
121.9 x 1.1 + 27.5 + 8 = 169.6 litres = 44,9 gallons

Question 3
33 x 97 ÷ 60 = 53.4 litres = 14.1 gallons
53.4 x 1.1 + 16.5 + 8 = 83.2 litres 22 gallons

Question 4
44 x 57 ÷ 60 = 41.8 litres = 11.1 gallons
41.8 x 1.1 +22 + 8 = 76 litres = 20.1 gallons

Question 5
60 x 308 ÷ 60 - 308 litres = 81.5 gallons
308 x 1.1 +30 + 8 = 376.8 litres = 99.7 gallons

Those are the answers I got, so thanks for confirming. The book has different answers!

That's really strange, because those answers we taken directly from the book and there have been no changes to that page since the 10% variable reserve was introduced.

Wow, strange indeed. Here's photographic evidence!

No idea what went on there! The current book and e-texts are correct. Obviously the error was found and a change was made but for some reason it has not been recorded in the errata. Thanks for your feed-back. It is most appreciated.