How can I know the half life of the new mixed sample?

Two samples of two different radioactive elements have their decay rates measured.
Both decay to only form stable isotopes.
K has a half life of 2.4 hours, and has a rate of 480 counts per minute.
L has a rate of 120 counts per minute.
straight after these measurements the samples were combine.
What is the count rate of the new mixed sample after 12 hours?

  1. What does “rate of x counts per minutes” mean?
  2. How can I solve this problem? the answer is “45 counts per minute”.

I guess this is a BMAT question but you have typed incorrect question because in the original half life of L was also given.

I saw the problem and typed it in the same way, so I probably saw the incorrect problem. :joy: I’ll have to look for the problem itself again. Thanks for letting me know!

When you find out please let me know also because what if its another question where we have to find answer without that information.

It’s not the same question, but pretty similar !