To construct a confidence interval using the given confidence level, do whichever of the following is appropriate. (a) find the critical value z subscript alpha divided by 2, (b) find the critical value t subscript alpha divided by 2, or (c) state that neither the normal nor the t distribution applies. 95%; nequals400; sigma is unknown; population appears to be skewed

Ineed with number 6 , explain how to get 1978

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.

When solving this problem: 3025/5.5 = a/90.75 you get 49912.5 which would be the length of one of the sides of a square when the area is only 90.75 inches. is that answer correct, why, and how is it possible?