#3 The sales tax on a $20 shirt was 9%.
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Answer:
And we can find this probability using the normal standard table or excel:
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the number of days before cartridge runs out of a population, and for this case we know the distribution for X is given by:
Where and
We are interested on this probability
And the best way to solve this problem is using the normal standard distribution and the z score given by:
If we apply this formula to our probability we got this:
And we can find this probability using the normal standard table or excel:
The slope of a line is the ratio of the change in y to the change in x. The slope of the given line is 1/2 = -6/-12. That is, when y changes by -6 to go from 6 to zero, x will change by -12 to go from 0 to -12.
The x-intercept is (-12, 0).
