The average mark of 18 students was calculated to be 65. However,it was later found out that the marks of one students had been wrongly entered as 24 instead of 34 and another 88 instead of 78. Find the correct average?

Open in App

Solution

Find the sum of the marks of 18 students :

Average = 65

Sum = 18 x 65 = 1170

Take away the wrong marks:

1170 - 24 - 88 = 1056

Add back the correct marks:

1056 + 34 + 78 = 1170

Find the correct average:

Sum = 1170

Average = 1170 ÷ 18 = 65

Answer: The average is still 65.

Suggest Corrections

Similar questions

Q. The average weight of

14

students was calculated as

71

. But it was later found that the weight of one student had been wrongly entered as

42

instead of

56

and of another as

74

instead of

32

. The correct average is

Q. The average height of 15 students is calculated as 75. But later it was found that the height of 1 student wrongly entered as 35 instead of 38 and another as 46 instead of 63.The correct average is

Q. The average marks secured by 15 students are 70 and later it was found that one entry is wrong and 65 is written instead of 45. Find out the corrected average.

A student's mark was wrongly entered as 86 instead of 66. Due to that the average marks for the class got increased by 1/2. What is the number of students in the class?

The average marks of 65 students in a class was calculated as 150. It was later realised that the marks of one of the student was calculated as 142, whereas his actual marks were 152. What is the actual average marks of the group of 65 students? (rounded off to two digits after decimal)

Join BYJU'S Learning Program

The average mark of 18 students was calculated to be 65. However,it was later found out that the marks of one students had been wrongly entered as 24 instead of 34 and another 88 instead of 78. Find the correct average?

Find the sum of the marks of 18 students : Average = 65 Sum = 18 x 65 = 1170 Take away the wrong marks: 1170 - 24 - 88 = 1056 Add back the correct marks: 1056 + 34 + 78 = 1170 Find the correct average: Sum = 1170 Average = 1170 ÷ 18 = 65 Answer: The average is still 65.

Find the sum of the marks of 18 students :

Average = 65

Sum = 18 x 65 = 1170

Take away the wrong marks:

1170 - 24 - 88 = 1056

Add back the correct marks:

1056 + 34 + 78 = 1170

Find the correct average:

Sum = 1170

Average = 1170 ÷ 18 = 65

Answer: The average is still 65.