Question

(b) The mean marks got by 300 students in the subject of statistics are 45. The mean of the top 100 of them was found to be 70 and the mean of the last 100 was known to be 20. What is the mean of the remaining 100 students?​

Answer 1

Answer: The mean marks of the remaining 100 students is 6000/100= 60.

Explanation: The mean marks of all the students is 45, and the mean marks of the top 100 students is 70, so the sum of the marks of the top 100 students is 70100=7000.

The mean marks of the last 100 students is 20, so the sum of the marks of the last 100 students is 20100=2000.

The sum of the marks of all the 300 students is 7000+2000+45*100=15000.

The sum of the marks of the remaining 100 students is 15000-7000-2000=6000.

The mean marks of the remaining 100 students is 6000/100= 60.