joselina
Answered

PLEASE SOMEONE HELP AND EXPLAIN THE FIRST ONE PLEASE SO THE HALF LIFE OF A RADIOACTIVE KIND OF POTASSIUM IS 12 HRS . HOW MUCH WILL BE LEFT AFTER 36 HRS, IF YOU START WITH 64 GRAMS OF IT? SO I DID A=64(1/2)^36 POWER IS THAT THE ACCURATE FORM PLEASE I NEED HELP ASAP

BTW THIS IS EXPONENTIAL DECAY

Verified Answer :

AL2006

Don't get carried away with the exponent.

The exponent is not the number of years or the number of hours.
The exponent is the number of half-lifes.

In this one, the half-life is 12 hours, and they want to know
how much is left after 36 hours.  36 hours is 3 half-lifes.
The formula that you did is beautiful and almost perfect.
Just change that ugly exponent to the number of half-lifes (3)
and the answer will jump out at you.

apologiabiology

half life formula is
F=P(1/2)^(t/h)

F=furure or ending amount
P=present amount
t=time elapsed
h=time the half life is


F=64(1/2)^(36/12)
F=64(1/2)^(3)
F=64(1/8)
F=8 grams

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