Please show steps This must be a short one What is the effec

Please show steps. This must be a short one.

What is the effective rate of interest on a loan at 0.5% every 2 weeks. 2) 1/2 life of radium is 34000 years. How long it will take to radiate 10%.

1) Effective rate of interest = (1 +r/M)^M -1

M =number of interest periods per year = 52/2 = 26

Effective annual rate of interest = (1 +r/M)^M -1 = (1+ 0.5/26)^26 -1 = 0.64 %

2) decay constant = 0.693/T1/2 = 0.693/34000

k =0.00002

N= No(e^(-kt)

N = 0.1No

So, 0.1 No = No e^(-0.00002t)

taking natural log:

ln(0.1) = -0.00002t

t = 115129.25 years