189k views
23 votes
You are saving money for a trip. Your plan is for each month to save 10% more money than the previous month. If you start with $100, how much will you have after 12 months? Round you answer to the nearest whole dollar.

User JezC
by
3.5k points

1 Answer

3 votes

Answer: $2,138

==========================================================

Step-by-step explanation:

We are summing terms of a geometric sequence with

  • a = 100 = first term
  • r = 1.10 = common ratio representing 10% increase

To find the sum of the first n terms of a geometric sequence, use this formula


S_n = (a(1-r^n))/(1-r)\\\\

We'll plug in the 'a' and r values mentioned, along with n = 12.


S_n = (a(1-r^n))/(1-r)\\\\S_(12) = (100(1-(1.10)^(12)))/(1-1.10)\\\\S_(12) \approx 2,138.428376721\\\\S_(12) \approx 2,138.43\\\\S_(12) \approx 2,138

After 12 months, you have saved about $2,138

User Abdulaziz
by
3.2k points