GK 2015 Q12
12. The mean score of the students who took a mathematics test was 6. Exactly 60% of the students passed the test. The mean score of the students who passed the test was 8. What was the mean score of the students who failed the test?
- A 1
- B 2
- C 3
- D 4
- E 5
Grey Kangaroo 2015, Question 12. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: C 3
Let the mean score of the 40% of the students who failed the test be \(x\). The information in the question tells us that \(0.6 \times 8 + 0.4 \times x = 6\). Hence \(0.4x = 1.2\) and so \(x = 3\).
Solution © UK Mathematics Trust, from the GK 2015 solutions.