Statistics please assist

The arithmetic mean of 20 observations from group A is 8, the arithmetic mean of 5 observations from group B is 12, and the arithmetic mean of 14 observations from group C is 16. If the three groups, A, B, and C, are merged, what is the arithmetic mean for the combined group? Select one: O 12 O 36 O 13 O 11.38The mean of a distribution is 43.0, the median is 24.0, and the mode is 21.5. It is most likely that this distribution is: Select one: symmetrical positively skewed asymptotic negatively skewed A random variable X has a probability distribution given by x 10 20 30 4o 50 P(X=x) 0.1 0.1 0.3 0.3 0.2 The expected value of X is Select one: 12 34 30 1300 Researchers claim that 60 tissues is the mean number of tissues a person uses during the course of a cold. The company that makes Kleenex brand tissues thinks that fewer of the tissues are used. In conducting a statistical test, what are the null and alternative hypotheses? Select one: O Ho: M 60 O Ho: u = 60 HI: M # 60If the coefficient of determination between an independent variable and dependent variable is 0.64, which of the following is the correct interpretation? Select one: O 64% of the total variation in the independent variable is explained by variation in the dependent variable O 64% of the total variation in the dependent variable is explained by variation in the independent variable O 80% of the total variation in the dependent variable is explained by variation in the independent variable O 0.64% of the total variation in the dependent variable is explained by variation in the independent variable