Complete the following:

1.The standard normal distribution has mean _____ and standard deviation _______. (2 marks)

2.The area under the density curve that lies between 30 and 40 is 0.832. What percentage of all possible observations of the variable are either less than 30 or greater than 40? (2 marks)

3.A curve has area 0.425 to the left of 4 and area 0.685 to the right of 4. Could this curve be a density curve for some variable? Explain your answer. (3 marks)

4.Determine the z-scores 0.03 and 0.005 . (4 marks)