Correct Answer - Option 2 : 60
Given:
Average marks obtained by 8 students = 51
Average marks obtained by 9 students = 68
Calculation:
Total marks obtained by 8 students = 51 × 8
⇒ 408
Total marks obtained by 9 students = 68 × 9
⇒ 612
The total marks obtained by 17 students = 408 + 612
⇒ 1020
Required average = 1020 /17
⇒ 60
∴ The average marks of all the students are 60.