Answer:
Sampling is necessary because researchers in the social sciences almost never have enough resources — time or money — to collect information about the entire set of subjects of interest to them.
Step-by-step explanation:
Sampling is done because you usually cannot gather data from the entire population. Even in relatively small populations, the data may be needed urgently, and including everyone in the population in your data collection may take too long.
If you're just starting calculus, perhaps you're asking about using the definition of the derivative to differentiate
.
We have

Expand the numerator using the binomial theorem, then simplify and compute the limit.

In general, the derivative of a power function
is
. (This is the aptly-named "power rule" for differentiation.)
What graph......................
ANSWER
307½ gallons of water
EXPLANATION
The volume of the rectangular swimming pool is

where l=25ft and w=20½ ft.
when it is filled to a depth of 4½ ft ,then the height is , h=4½ ft.
We substitute these values into the formula to get:


If one cubic foot of water is 7½ gallons, then 2306.25 cubic feet will be

We need 307.5 gallons of water to fill the pool.