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Exponential Decay

In physics, exponential decay is a process where a quantity decreases over time at a rate proportional to its current value.

We've found that LockedIn influencers tend to lose followers similarly. This means that the more followers you have, the faster you lose them.

Assignment

Complete the decayed_followers function.

It calculates the final value of a quantity after a certain time has passed, given its initial value and a rate of decay. Return the remaining followers.

remaining_total = quantity * ( retention_rate ^ time )

The retention_rate is the opposite of fraction_lost_daily. If an influencer lost 0.2 (or 20%) of their followers each day, then the retention rate would be 0.8 (or 80%).

Example

With these parameters:

initial_followers = 100
fraction_lost_daily = 0.5

Then we expect these results:

After 0 days: 100 followers
After 1 day: 50 followers
After 2 days: 25 followers
After 3 days: 12.5 followers (rounded down)

This isn't the exact formula shown on Wikipedia, but it's the same idea.