Problema Solution

If your allowance was a penny doubled every day, how many days would it take for you to have over $1000?

Answer provided by our tutors

The number of pennies give are elements of geometric series with ratio r = 2 and first element 1 penny.

The number of the first n members of this geometric sequence is:

S = 1*(1 - 2^n)/(1 - 2)

S = 2^n - 1

We need to solve

2^n - 1 <= 1000

2^n <= 1001

........

click here to see the solving for n

........

n <= 9.96

It will take 10 days to have over $1000.