Here goes! If you read the explanation of turning error in the book you will appreciate that in this question the compass will end up overreading due to this particular problem (ie the indicated heading will be greater than the correct heading). With regard to the amount of over read we believe most schools use a rather simplified approach as follows:

Required Final Heading Turning Error

360 - 030 30 degrees

030 - 060 20 degrees

060 - 090 10 degrees

090 - 120 10 degrees

120 - 150 20 degrees

150 - 180 30 degrees

180 - 210 30 degrees

210 - 240 20 degrees

240 - 270 10 degrees

270 - 300 10 degrees

300 - 330 20 degrees

330 - 360 30 degrees

Therefore;

(1) to roll out on a correct heading of 180 you will need to see 180+30 on the compass

(2) to roll out on a correct heading of 360 you will need to see 360+30 on the compass