Question:
A group of students were calculating their average height. They found that if one of them was 15 cm taller, their average height will be 142 cm. However, it one of them was 9 cm shorter, their average height would be 139 cm. How many students were there in the group?
Solution:
![P6 / ACS / 2018 / SA2 / Paper 2 – Q13 [4 marks]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2019/07/P6_ACS_2018_Prelims_Paper2_Q13-e1561993008586.jpg?resize=400%2C260&ssl=1)
![P6 / Catholic High / 2019 / SA1 / Paper 2 – Q09 [3 marks]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2020/04/P6_Catholic_2019_SA1_Paper2_Q09-Qns.jpg?resize=400%2C260&ssl=1)