For the following questions answer them individually
If $$n_1 = 10$$ and $$n_2 = 5$$, are the sizes, $$\overline{x}_1, = 7$$ and $$\overline{x}_2, = 4$$ are the means and $$\sigma_1 = 1$$ and $$\sigma_2 = 1$$ are the standard deviations of two series of data. If combined mean $$\overline{x}_2, = 6$$, then the variance of the combined series with size $$n_1 + n_2$$ is equal to:
X and Y are independent normal variables with mean 50 and 80 respectively and standard deviation as 4 and 3 respectively. What is the distribution of X + Y ?
The following observations 14, 19, 17, 20, 25 constitute a random sample from an unknown population with mean $$\mu$$ and standard deviation $$\sigma$$. The point estimation of population mean is:
A man pedals cycle from his house to his office at a speed of 10 km/h and back from the office to his house at a speed of 15 km/h. H is average speed (in km/h) is:
