The average mark of 24 students is 60. When 6 more students join, the average mark of all 30 students becomes 58. What is the average mark of the 6 new students?

Explanation

1. 01

   Old total = $24 \times 60 = 1{,}440$.

2. 02

   New total = $30 \times 58 = 1{,}740$.

3. 03

   The 6 new students scored $1{,}740 - 1{,}440 = 300$ in all, an average of 50.