The average of the marks of 20 students is 72. Later, it was found that the marks of two students were wrongly entered as 48 and 56 instead of 84 and 65. Find the correct average.
74.25
Original (incorrect) total of 20 students \(= 20 \times 72 = 1440\).
Correction: subtract the wrong entries 48 + 56 = 104 and add the right entries 84 + 65 = 149; net addition = 149 − 104 = 45. Correct total \(= 1440 + 45 = 1485\).
Correct average \(= 1485 / 20 = 74.25\).
Hence, 74.25.
Important Questions from Average
Average of 40 numbers is 71, if the number 100 replaced by 140, then average is increased by
The captain of a football team of 11 members is 28 years old and the goalkeeper is 4 years older than him. If the ages of these two are removed, then the average age of the remaining players is two years less than the average age of the whole team. What is the average age of the team?
There are two Classes A and B having 25 and 30 students respectively. In Class-A the highest score is 21 and lowest score is 17. In Class-B the highest score is 30 and lowest score is 22. Four students are shifted from Class-A to Class-B.
Consider the following statements:
1. The average score of Class-B will definitely decrease.
2. The average score of Class-A will definitely increase.
Which of the above statements is/are correct?
The average weight of A, B, Cis 40 kg, the average weight of B, D, Eis 42 kg and the weight of Fis equal to that of B. What is the average weight of A, B, C, D, Eand F?
A cow costs more than 4 goats but less than 5 goats. If a goat costs between Rs. 600 and Rs. 800, which of the following is a most valid conclusion?
