The ratio of boys to girls in the 10th grade is 8 to 13. If there are 91 girls in 10th grade, then how many boys are there?

The population is 168,900,000 to the nearest hundred thousand

Step-by-step explanation:

In this question, we are tasked with calculating the population of Brazil given its population in 1995 and her growth rate per decade.

Mathematically, we use an exponential function to calculate this population.

This can be written as P = I(1 + r)^n

where P is the population in 2015 which we are looking for,

I is the initial population which is 162,300,000

r is the rate of increase per decade given as 2% = 2/100 = 0.02,

n is the number of times between the years we are expecting this growth. The difference between the years 2015 and 1995 is 20 years which signifies 2 decades(1 decade is 10 years). Thus our n is 2

We plug these values into the equation above;

P = 162,300,000(1+0.02)^2

P = 162,300,000(1.02)^2

P = 168,856,920 which is 168,900,000 to the nearest hundred thousand