Answer: 
Step-by-step explanation:
Here, According to the question, The population of the world is 4 billion (approx).
Again According to the question, The world's population has grown at an average rate of 1.9 percent per year since 1945.
Therefore, after 1975 the growth rate will remains same.
Thus, the population of the world after t years,
(By the formula 
)
⇒
Where 1.019 is the growth rate and 4 billion is the initial population.
C=6.28cm
because C=2pi•r
so in this case C=2•3.14•1
which is C=2•3.14
and that leads to C=6.28cm
hope this helped
Would it be y2 ? idk im not sure but i tried
Answer:
a1 = 2
d = 3
an = 2 + (n - 1) * 3
a7 = 20
a59 = 176
Steps:
a1 is the initial value (when n equals 1), and since there are 2 crosses, it is 2.
d is the added value to each amount of crosses. And since the second amount is 5 and the third amount is 8, we can determine that each n is adding 3 crosses, therefore making d = 3.
The equation is simply plugging in the values for a1 and d.
A7 is simply plugging in 7 for n in the equation and solving for it. So;
a7 = 2 + (7 - 1) * 3
a7 = 2 + 6 * 3
a7 = 2 + 18
a7 = 20
And same thing as the last for 59 except substitute 59 in for where you put 7;
a59 = 2 + (59 - 1) * 3
a59 = 2 + 58 * 3
a59 = 2 + 174
a59 = 176
It is 39
Because you have to count the little dots all the way till it is around the most age.
