What `%` age of a given mass of a radioactive substance will be left undecayed after five half life periods?

What percentage of a radioactive substance will left undecayed after four half-life periods?

The fraction of the radioactive sample will remain undecayed after 4 half-life periods is

What percentage of radioactive substance is left after 5 half lives?

The percentage of radioactive substance left after 5 half lives is

The decay constant of a radioactive substance is 1 per month. The percentage of radioactive substance left undecayed after two months will be

What percentage (approximate) of original radioactive substance left after 4 half-Life?