Scheming

Algebra Level 3

A fraudster creates a new scheme. It nets him $1,000 during the first week, $2,000 during the second week, $4,000 during the third week, and so on, doubling every week.

How many weeks will it take for him to accumulate over a million dollars with his scheme?

8 9 10 11

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

2 solutions

Denton Young
Nov 9, 2016

The cumulative total:

After week 1 --1000 dollars

After week 2 -- 3000 dollars

After week 3 -- 7000 dollars

After week N, the accumulated total is ( 2 N 1 ) × 1000 (2^N - 1) \times 1000 dollars.

This becomes more than a million dollars at N = 10.

I wish I could get that much money

Razzi Masroor - 4 years, 7 months ago

Log in to reply

Go talk to Bernie Madoff and ask him for assistance in creating a scheme. :)

Denton Young - 4 years, 6 months ago
Viki Zeta
Nov 10, 2016

It's GP.

a = 1000 , r = 2 S n = 1000 ( 1 2 n ) 1 2 1000000 = 1000 ( 1 2 n ) 1 1000 = 1 2 n 2 n = 1001 n 9.96 n = 10 S n > 1000000 a = 1000, r =2 \\ S_n = \dfrac{1000 (1 - 2^n)}{1-2} \\ 1000000 = \dfrac{1000(1-2^n)}{-1} \\ -1000 = 1 - 2^n \\ 2^n = 1001 \\ n \approx 9.96 \\ \boxed{\therefore n=10 \implies S_n > 1000000}

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...