Halimah Medispa Sdn. Bhd. offers a launching promotion. For every 2 friends referred, the membership fee will be exempted. The spa expects to close the promotion when they reach the 500th membership. Starting with only 1 member, membership is targeted to grow at a rate of 12% daily. How long will the promotion
last?
1.12^x = 500
x = ln500/ln1.12 = ____