What is the function of stewards in a wiki website?

How do astronomers measure the amount of dark matter in the universe

The average act score follows a normal distribution, with a mean of μ = 21.1 and a standard deviation of σ = 5.1. what is the probability that the mean iq score of 50 randomly selected people will be more than 23? 0 1 0.9958 0.3547 0.0042

Which of the following characterize the historical move toward urbanization? i. increase in pollution ii. increase in frequency of natural disasters iii. increase in incidence of infectious disease a. i b. ii c. i and ii d. i and iii e. i, ii and iii