Question

Daniel calculated his average over the last 24 class tests and found it to be 76. He finds out that the marks for three tests have been inverted by mistake. The correct marks for these tests are 87, 98 and 79. What is the approximate percentage difference between his incorrect average and his actual average?

Answer 1

There will be no change in the average

Step-by-step explanation:

Step 1 of 4

According to the given information, the numbers were inverted. That means

87=78

98=89

79=97

Step 2 of 4

From the formula of average, we know

average = sum /total number of inputs

Step 3 of 4

We need to subtract the incorrect numbers and add the correct ones

Sum = x-78-89-97+87+98+79

Sum = x-0

Step 4 of 4

Since there is no change in the sum. We conclude, that there will be no change in the average as well.