posted by Jannie .
In a test there were 25 multiple-choice questions. They were marked as follows:
2 marks for each correct answer
0 marks for a non-attempt
1 mark for an incorrect answer.
5 of the questions and received 22 marks. How many questions did
she answer correctly?
Again we can set this up as two simultaneous equations
2 marks for each correct answer A
0 marks for a non-attempt (not interested in these)
1 mark for an incorrect answer B
A+B=20 (she only answered 4/5 of 25 questions)
2A+B=22 based on the marks
solve the two for A