The mean lives of an unstable nucleus in two different decay processes are 1620 yr and 405 yr, respectively. Find out the time during which three-fourth of a sample will decay.

The mean lives of a radioactive substance are 1620 years and 405 years of alpha -emission and beta -emission respectively. Find out the time during which three-fourth of a sample will decay if it is decaying both by alpha -emission and beta -emission simultaneously.

The mean lives of a radioactive substance are 1620 years and 405 years for alpha emission and beta emission respectively. Find out the time during which three fourth of a sample will decay if it is decaying both by alpha -emission and beta -emission simultaneously. (log_e4=1.386).

The mean lives of a radioactive substance are 1620 years and 405 years for alpha emission and beta emission respectively. Find out the time during which three fourth of a sample will decay if it is decaying both by alpha -emission and beta -emission simultaneously. (log_e4=1.386).

The mean lives of a radioactive substance are 1620 years and 405 years of alpha -emission and beta -emission respectively. Find out the time during which three-fourth of a sample will decay if it is decaying both by alpha -emission and beta -emission simultaneously.