3 The mean and standard deviation of 20 values of \(x\) are 60 and 4 respectively.
- Find the values of \(\Sigma x\) and \(\Sigma x ^ { 2 }\).
Another 10 values of \(x\) are such that their sum is 550 and the sum of their squares is 40500 . - Find the mean and standard deviation of all these 30 values of \(x\).