Given the data provided, it follows that the farmers must wait for 26 days before feeding the hay to cows.
What is half life?
The term half life is defined as the time taken for half of the original amount of the radioactive sample to remain.
Now we know that;
half life = 8 days
Original amount = No
Amount left after t days = 0.1No
time taken = t days
Hence;
0.693/8 = 2.303/t log (No/0.1No)
0.087 = 2.303/t
t = 2.303/0.087
t = 26 days
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