How would I go about solving these problems?

Question

In Exercise 9 we suggested the model N(1152,84) for weights in pounds of yearling Angus steers. What weight would you consider to be unusually low for such an animal? Explain.

If you are given the model N(1152,84),what are the cutoff values for the middle 40% of the weights?

Answer 1

I assume that you are talking about a normal distribution with a mean of 1152 and standard deviation of 84.

A Z score is the score in terms of standard deviations (SD), with -2 SD usually being considered low.

Z = (x - ƒÊ)/SD, where x = weight value and ƒÊ = mean. Solve for the unknown, once you find the Z score

The middle 40% is ƒÊ �} 20%.

Look up the various Z score values in the table in the back of your statistics booklabeled something like "areas under the normal distribution."

I hope this helps. Thanks for asking.