The monthly spending on food of a family of three in Puerto Rico for the year 2000 is estimated in an average of $420.00/month with a standard deviation of $80.00. Assuming that the monthly spending in food is distributed normally (when presenting the processes, you need to include the corresponding graphs.):
a) What proportion of the spending is lower than $350.00?
b) Which percentage of the spending is between $250.00 and $350.00?
c) Which percentage of the spending is lower than $250.00 or higher than $450.00?
d) What proportion of this spending is larger than $420.00?
e) Which percentage of this spending is between $490.00 and $590.00
The solution gives the complete steps of calculating probability based on Z score and normal distribution.