GK 2017 Q1
1. A group of girls stands in a circle. Florence is the fourth on the left from Jess and the seventh on the right from Jess. How many girls are in the group?
- A 9
- B 10
- C 11
- D 12
- E 13
Grey Kangaroo 2017, Question 1. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: C 11
Since Florence is the fourth on the left from Jess, there are three girls between them going left round the circle. Similarly, since Florence is the seventh on the right from Jess, there are six girls between them going right. Therefore there are nine other girls in the circle apart from Florence and Jess. Hence there are 11 girls in total.
Solution © UK Mathematics Trust, from the GK 2017 solutions.