Answer:
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".
Let X the random variable that represent interest on this case, and for this case we know the distribution for X is given by:
And let represent the sample mean, the distribution for the sample mean is given by:
On this case
Solution to the problem
We want this probability:
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:
Answer:
Sebastian didn't interpret the numbers correctly (See explanation)
Step-by-step explanation:
If you go up an elevator, you are gaining floors, so the number is positive.
If you go down an elevator, you are losing floors, so the number is positive.
Looking at the statement, he went 7 floors up to his room, then 9 floors down to the parking garage this can be represented as , since the 7 is positive and the 9 is negative.
Sebastian described the movement as , which is wrong - 9 should be -9 and -7 should be 7.
Hope this helped!