I incorrectly calculated vat by adding 20% instead of 20/120 in June 2016 exam. In question, it was stated that all amounts are exclusive otherwise stated. I want to know that because of this mistake, my whole question will be wrong?
No your whole answer will not be wrong but clearly you will lose some marks if you computed the VAT incorrectly – that said if the question stated that the amounts were exclusive of VAT then you should indeed have used 20% and only applied 20/120 where it specifically stated that it was inclusive!