The Amazon rainforest is gradually being destroyed by pollution and agricultural and industrial development. For simplicity, suppose that each year, 10% of the remaining forest is destroyed. Assume, also for simplicity, that the present area of the Amazon rainforest is 1,200,000 square miles.
1.a) What will the area of the forest be after 1 year of this destruction process?
1.b) What will the area of the forest be after 2 years of this destruction process?
2) Make a graph showing your results from Question 1 and continuing through 5 years of the destruction process. Include the present situation as a point on your graph.
3) Find a rule for how much rain forest will remain after X years. That is, express the area of the rain forest as a function of X.
Answer:
Step-by-step explanation:
If the first floor of the Willis Tower is 21 feet high. and each additional floor is 12 feet high, then the floor heights as we move from one floor to another we keep increasing by 12feets and forms an arithmetic progression as shown;
21, (21+12), (21+12+12), ...
<em>21, 33, 45...</em>
a) To write an equation for the nth floor of the tower, we will have to find the nth term of the sequence using the formula for finding the nth term of an arithmetic sequence.
The nth term of an arithmetic sequence is expressed as 
a is the first term = 21
d is the common difference = 33-21 = 45-33 = 12
n is the number of terms
Substituting the given parameters into the formula;
<em>Hence the equation for the nth floor of the tower is expressed as </em>
<em></em>
<em></em>
b) To get the height of the 65th floor, we will substitute n = 65 into the formula arrived at in (a)
<em>Hence the height of the 65th floor is 789feets.</em>
Answer: 5
“of boys to girls”
( 3 ) : ( 5 )
The more painstaking way would be to divide the spinner up into 100 pieces, and shade in 5 of those pieces. Since 5/100 = 0.05 = 5% this means that landing on any of the 5 pieces has a 5% chance of happening.
A better way to do this is to use 20 slices instead. This works because 5/100 reduces to 1/20 (divide top and bottom by 5). Instead of shading in 5 slices, Mark should shade in 1. If you use a calculator, you should see that 1/20 = 0.05 = 5% as well.
The second option is more practical but even then a spinner with 20 sections is still a lot. I think it might be better for Mark to pull random numbers out of a hat, or let the computer generate random numbers.
