SOLUTION: I have tried to setup this word problem, but I am having difficulty doing so. Here is the problem: An investment of $1000 doubles every 7 years, after 28 years how much would the

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Question 5401: I have tried to setup this word problem, but I am having difficulty doing so. Here is the problem:
An investment of $1000 doubles every 7 years, after 28 years how much would the investment be. I have tried:
1000(2)x 28 = 7
2000 (28) = 7
56000 = 7
56000/7 = 8000
I know the answer is 16, but I am not setting something up correctly. Please Help
TSJ

Answer by Abbey(339) About Me  (Show Source):
You can put this solution on YOUR website!
Look at it this way:
If x = the initial investment, then the percentage increase * the initial investment = final value
If it is doubling each 7 year period, then there are 4 periods of 7 years in our time frame of 28 years
This is represented as 2%5E4x
Another way to look at it, is as follows:
2x= the investment in year seven,
2(2x)= 4x the investment in year 14
2(4x)= 8x the investment in year 21
2(8x) = 16x the investment in year 28
So if we plug in the value of x = ($1000), then
16($1000)=$16,000