In a radioactive sample 4019K nuclei either decay into stable 4020Ca nuclei with decay constant 4.5×10−10 per year or into stable 4018Ar nuclei with decay constant 0.5×10−10 per year. Given that in this sample all the stable 4020Ca and 4018Ar nuclei are produced by the 4019K nuclei only. In time t×109 years, if the ratio of the sum of stable 4020Ca and 4018Ar nuclei to the radioactive 4019K nuclei is 99, the value of t will be? [Given: In 10=2.303]