Write an expression for the total cost of movie tickets and popcorn for a group of friends attending a movie, x, if: Movie ticke
1 answer:
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Answer:
d. Cannot be determined with the information provided.
Step-by-step explanation:
Z-score:
In a set with mean and standard deviation
, the z-score of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
Finding the better relative position:
The score with the better relative position is the one with a higher z-score.
To find the z-score, the mean and the standard deviation is needed, and in this question, the standard deviation is not given, and thus, the correct answer is given by option d.
This should do it...hope it helps!!
Answer:
And if we solve for a we got
So the value of height that separates the bottom 10% (Fastest 10%) of data from the top 90% is 393.2.
so if the time is 393.2 or lower a boy would earn a certificate of recognition from the fitness association
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 time for this event of a population, and for this case we know the distribution for X is given by:
Where and
NOTE: For this case the fastest 10% is on the lower tail of the distribution
For this part we want to find a value a, such that we satisfy this condition:
(a)
(b)
Both conditions are equivalent on this case. We can use the z score again in order to find the value a.
As we can see on the figure attached the z value that satisfy the condition with 0.1 of the area on the left and 0.9 of the area on the right it's z=-1.28. On this case P(Z<-1.28)=0.1 and P(z>-1.28)=0.9
If we use condition (b) from previous we have this:
But we know which value of z satisfy the previous equation so then we can do this:
And if we solve for a we got
So the value of height that separates the bottom 10% (Fastest 10%) of data from the top 90% is 393.2.
so if the time is 393.2 or lower a boy would earn a certificate of recognition from the fitness association