if the randon error in the arithmetic mean of 50 observations is `alpha`, then the random error in the arithmetic mean of 150 observations would be

The random error in the arithmetic mean of 50 observations is 'a', then the random error in the arithmetic mean of 200 observations would be ............

The random error in the arithmetic mean of 100 observations is x, then random error in the arithmetic mean of 400 observations would be

The random error in the arithmetic mean of 100 observations is x, then random error in the arithmetic mean of 400 observations would be

If arithmetic mean of 9 observations is 100 and that of 6 is 80 .Then the combined mean of all the 15 observations will be

If arithmetic mean of 9 observations is 100 and that of 6 is 80 .Then the combined mean of all the 15 observations will be

The arithmetic mean of 12 observations is 15. If two observations 20 and 25 are removed then the arithmetic mean of remaining observations is

The arithmetic mean of 11 observations is 11. The arithmetic mean of the first 6 observations is 10.5 and the arithmetic mean of the last 6 observations is 11.5. What is the sixth observation ?

The arithmetic of 12 observations is 15. If two observations 20 and 25 are removed then the arithmetic mean of remaining observations is