Because of cholesterol problems, I must take a certain medicine. Every week I buy a box, which lasts me for seven days.

However, things are not so bad. The laboratory that produces this medicine has an standing offer: for every five empty boxes, they give you a free new box.

Thus, I get six boxes paying just for five; it means a 16.67% savings for me... right or wrong?

Wrong.  Only if the treatment were to last 6 weeks, then the savings would be approximately 16.67%, but as weeks and years pass the savings approaches the limit of 20%.

With an assumption that e.g. began his medication at a youthful
age of 22 years and would have the longevity rivaling Jeanne
Calment (122 years), and with all other relevant factors equal,
he could only expect an approximate 19.98397% to 19.99936% savings on medication. The lower percentage limit in savings given is that e.g. may end his medication with five empty boxes and no new purchase. The upper percentage limit in savings is for the week of the acquisition of the last free new box for five empties. 

Posted by Dej Mar on 2006-08-11 13:17:06