List of top Mathematics Questions on Mean

The function \[ f(x)=\sum_{k=1}^{7}(x-k)^2 \] has a minimum value at \(x=a\). Then, \(a\) is equal to:
10 people went to a restaurant to have a meal as a group. Of these, 9 had already contributed Rs 400 each, while the 10th person had to give the entire additional amount required to honour the restaurant's bill. How much did this person pay if he had to pay Rs 900 more than the group's average?
The average weight of 24 students in a class is 52 kg. If the weight of the teacher is added, the average increases by 1 kg. Find the weight of the teacher.
If the mean of 5 observations x, x+2, x+4, x+6 and x+8 is 11, then value of x