SOLUTION: I am trying to prepare for my test and I have absolutely no idea how to do this! Each month, an American household generates an average of 28 pounds of newspaper for garbage or

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Question 921798: I am trying to prepare for my test and I have absolutely no idea how to do this!
Each month, an American household generates an average of 28 pounds of newspaper for garbage or recycling. Assume the variable is approximately normally distributed and the standard deviation is 2 pounds. If a household is selected at random, find the probability of its generating:
a. Between 27 and 31 pounds per month
b. More than 30.2 pounds per month
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
given: an average of 28 pounds
a.
Find z values corresponding to 27 and 31:

z=%2827-28%29%2F2=-1%2F2=-0.5
z=%2831-28%29%2F2=3%2F2=1.5

Find the area between z+=+-0.5 and z=+1.5
Table E gives us an area of 0.9332-0.30=0.6247=> The probability is 62.47%
b.
Find z values corresponding to 30.2
z=%2830.2-28%29%2F2=2.2%2F2=1.1 Find the area to the right of z+=1.1
it gives you an area of 0.1357=> The probability is 13.57%