geometric series word problems

[PixiePink]

I need help setting up these geometric series problems:

A city has a population of 20,000 people in the year 2000. If the population increases 5% per year, what will the population be in 2010? ( You are not summing the population over 2000-2010. Find the population in the year 2010, use a1r^n to solve.)

&

At the age of 21, Cyndi began receiving yearly payments from a trust fund. On each succeeding birthday, she received twice as much as in the preceding year. If she had received a total of $303,800 by age 25, how much did she receive at age 21?

 

[Denis]

I need help setting up these geometric series problems:

A city has a population of 20,000 people in the year 2000. If the population increases 5% per year, what will the population be in 2010? ( You are not summing the population over 2000-2010. Find the population in the year 2010, use a1r^n to solve.)

&

At the age of 21, Cyndi began receiving yearly payments from a trust fund. On each succeeding birthday, she received twice as much as in the preceding year. If she had received a total of $303,800 by age 25, how much did she receive at age 21?

First one: 20000 * (1.05)^10
Formula: A(1+r)^n

2nd one: x,2x,4x,8x,16x : that's 31x = 303800

OK?