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.
Answer:
x= 81°, z= 99°, y°=68°
Step-by-step explanation:
considering the part of the triangle where 36° , 63° and x° is located as ΔABC.
to find the measure of x we use angle sum property.
We know that the sum of the angles of a triangle is always 180°. Therefore, if we know the two angles of a triangle, and we need to find its third angle, we use the angle sum property. We add the two known angles and subtract their sum from 180° to get the measure of the third angle.
so,
∠A + ∠B +∠C = 180°
36° + 63° + x° = 180°
99° + x° = 180°
x° = 180 - 99
x° = 81°
When two lines intersect each other at a single point, linear pairs of angles are formed. If the angles so formed are adjacent to each other after the intersection of the two lines, the angles are said to be linear. If two angles form a linear pair, the angles are supplementary, whose measures add up to 180°.
x° + z° = 180°
81° + z = 180°
z= 180 - 81
z= 99°
considering the next part of the triangle where 13° , z° and y° is located as ΔACD
to find the measure of y we use angle sum property.
∠A + ∠C + ∠D = 180°
13° + z° + y° = 180°
13°+99°+y°= 180°
112°+ y° = 180°
y°= 180- 112
y° = 68°
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