Could someone who is better at math tell me, what would Weekly rate have to drop to, to make yearly 70% the better option?
1 month has 4 weeks.. so 4 x 12 = 48 then 70% divide by 48 = 1.45%
1.45% weekly is equivalent to 70% yearly
so if weekly rate is 1.40% ( 67.2% yearly if you park weekly) .. Then yearly parking will be the best option at 70%.
There are 52 weeks in a year and not 48 (divide 365/7...) and the correct formula to turn a yearly rate into a weekly rate is the following one :
((1 + yearly rate in percentage/100)^(1/52) - 1) * 100
70% annual is (approx.) 1,0256% weekly.
Remember, interests are cumulative. You get interests on previously earned interests, you just can't divide the yearly rate.