Q19
ArithmeticAverages & Ages
The average of marks of 28 students in Mathematics was 50. Eight students left the school and then this average is increased by 5. What is the average of marks obtained by the students who left the school?
- a.37·5
- b.42·5
- c.45
- d.50·5
Answer: (A) 37·5
Total for 28 students = 1400; the remaining 20 students average 55, totalling 1100. The 8 who left scored 1400 − 1100 = 300, an average of 300 ÷ 8 = 37·5. The other options would leave the new average different from 55.