Answer:
Percentage increase = 269%
Step-by-step explanation:
Price of a DVD last week = $2.87
Price of the same DVD this week = $10.59
Increase in the price of DVD between last week and this week = 10.59 - 2.87
= $7.72
Therefore, percentage increase in the price of DVD = 
= 
= 268.99
= 269%
Answer:

And we can solve this using the following z score formula:

And if we use this formula we got:

So we can find this probability equivalently like this:

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 heights of a population, and for this case we know the distribution for X is given by:
Where
and
We select n =100. Since the distribution for X is normal then we know that the distribution for the sample mean
is given by:
We want this probability:

And we can solve this using the following z score formula:

And if we use this formula we got:

So we can find this probability equivalently like this:

Answer:
x=4.5
y=5.75
Step-by-step explanation:
since you dont have much time to wait, i wont put an explanation here