The number of orders received daily by an online vendor of used CDs is normally distributed with mean 270 and standard deviation
1 answer:
Answer:
Step-by-step explanation:
Given that the number of orders received daily by an online vendor of used CDs (say X) is normally distributed with mean 270 and standard deviation 16.
X is N(270, 16)
To find percentage of days will the company have to hire extra help or pay overtime, we can find probability using std normal table
X>302 means
P(Z>2) = 0.25
Thus 25% of days will the company have to hire extra help or pay overtime
You might be interested in
Answer:
A. 13.9 and 14.1 inches
See explanation below.
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 outside diameters of a population, and for this case we know the distribution for X is given by:
Where and
If we want the middle 68% of the data we need to have on the tails 16% on each one
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 0.16 of the area on the left and 0.84 of the area on the right it's z=-0.994. On this case P(Z<-0.994)=0.16 and P(z>-0.994)=0.84
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
And since the distribution is symmetrical for the upper limit we can use z = 0.994 and we have:
And if we solve for a we got
So the correct answer for this case would be:
A. 13.9 and 14.1 inches