A student scored 70, 80, 75, and 85 in four subjects. What score must he get in the fifth subject to have an average of 80?

Question: A student scored 70, 80, 75, and 85 in four subjects. What score must he get in the fifth subject to have an average of 80?

Solution:
- If the average is 80, then
- Total marks needed = 80 × 5 = 400
- Marks so far obtained in 4 subjects = 70 + 80 + 75 + 85 = 310
- Marks Required to obtain desired average = 400 - 310 = 90