Answer:
The relationship between the circumference of a circle and its diameter represent a direct variation and the constant of proportionality is equal to the constant 
Step-by-step explanation:
we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form 
where K is the constant of proportionality
In this problem we know that
The circumference of a circle is equal to

therefore
the relationship between the circumference of a circle and its diameter is a direct variation and the constant of proportionality is equal to the constant 
Answer:
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
Since the distribution for X is normal then the we know that the distribution for the sample mean
is given by:
And the standard error is given by:

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
Since the distribution for X is normal then the we know that the distribution for the sample mean
is given by:
And the standard error is given by:

First, find the rate of flowers bought per hour:
48 / 3 = 16 flowers per hour.
Then, to find the amount bought after 2 hours, multiply the 16 flowers per hour by 2.
16 * 2 = 32.
After 2 hours, she will have bought 32 flowers.
From the given equation above, F = ma, acceleration may be calculated by slightly modifying the equation into a = F / m. Substituting the known values for force and mass,
a = 2,050,000 N / 40,000 kg = 51.25 m/s²
Thus, the acceleration achieved is 51.25 m/s².