Staals half
1 gram left
0.3 grams left
half lives are normally written in years
it goes likt this

A=final amount
P=initila amount
t=time elapsed
h=time half life is (same units as time)
let's use days as the units of time
we are given
initial amount=1gram
final amount=0.3gram
time=4 days
so

solve for h

take the ln of both sides


times both sides by h

divide both sides by ln(0.3)

use calculator
h=2.30287
3 sig figs
h=2.303 days
(−0.0081p)(t)=(15000)(2.718282)
Step 1: Divide both sides by -0.0081t.
−0.0081pt
−0.0081t
=
40774.227427
−0.0081t
p=
−40774.227427
0.0081t
Answer:
p=
−40774.227427
0.0081t
Hi there!
Okay, so I was a bit confused by your question, but I tried to make it a bit easier and work out.
There was two ways I did this because I didn't want to NOT answer your question!
What about this:
3.2/15 cannot be simplified lower than what it is. Decimal form is 0.2133333 (repeating). I answered this part because I didn't know what 3. was (I at first thought it was part of the numerator. But now that I look at it again it may have been a question number. But just in case, I answered it like this anyway.)
Next!
I solved 2/15, which also cannot be simplified down lower than what it is. It's decimal form is 0.133333 (another repeating decimal.)
And so as you can see I answered two problems for you. If these are incorrect, let me know!
Hope this helps!
The square root of 3.24 is 1.8