Answer:
Left amount of Polonium-210 after 115 days will be 4.5927 microgram
Step-by-step explanation:
We have given initial mass of Polonium-210

Decay rate x= 0.502% = 0.00502
Time t = 115 days
We have to find the left amount of Polonium -210 after 115 days
We know that left amount is given by

So left amount of Polonium-210 after 115 days will be 4.5927 microgram