Answer: 65
Step-by-step explanation:
Since the mean mark of the 9 students is 50. Their total marks will be:
= 9 × 50
= 450
Since the marks obtained by 8 students are given, we add the marks together and this will be:
= 60+40+50+30+80+40+45+40
= 385
The score of the 9th student will be:
= 450 - 385
= 65