Answer:
Great work!
Step-by-step explanation:
These kind of questions are calculated through Riemann Sum. You can evaluate any definite integral using the Riemann Sum. It should be in the following form:
f(x)dx on the interval [a, b], or

Now f(x) is simply y. Therefore in this example y = x^3 - 6x. We just need the sufficient amount of data to apply the Riemann Sum, including the interval [a, b] that bounds the area, and the the number of rectangles 'n' that we need to use.
Consider an easier approach to this question: (First attachment)
Graph: (Second Attachment)
So.... notice the picture below
now, we know what the "height" or "altitude" is
now, we also know the perimeter is 18cm
so, k + k + b = 18
or 2k + b = 18
thus

so... one can say that

and you can simplify it if you wish.. not sure you have to
3000000÷1.125=2666666.6667
Round off to 2666667 people.
Feel free to correct this if wrong.
Answer:
The sampling method used is a stratified sampling method
Step-by-step explanation:
sampling is the selection of a predetermined representative subpopulation from a larger population, to estimate the characteristics of the whole population.
Stratified sampling: Here, the total population are divided into subcategories (strata) before sampling is done. The strata are formed based on some common characteristics. In our example, the times of the day (morning, afternoon and evening) has widely varying atmospheric conditions which will add biases to the measurement of air quality. For example, the air in the morning if compared to the afternoon in an industrial area may be purer because of minimal industrial activity, hence effective comparison will be made by stratification.
-6x + 5 > -1
-6x > -1 - 5
-6x > -6
x < -6/-6
x < 1 <===