Question

A stock loses half its value each week. If the stock started at $125, what is it worth after 4 weeks?

Answer 1

Answer: 7.81

The formula is

y = 125* (1/2)^4

y = 125 / 16

y = 7.81

So at the end of the 4th week, the stock is worth only 7.81 dollars.

If that is not the motive and the first week doesn't count then the formula changes to...

y = 125 * (1/2)^(n-1)

y = 125 * (1/2)^3

y = 15.625 could be the other answer if you looked at it in that perspective

However, I would go with 7.81 as the answer.

Hope I helped :)