Answer:
a) Two half lives, b) 
Step-by-step explanation:
a) The polonium-210 has a half life of 138.4 days. Therefore, 1.994 half lives have past.
b) Mass decay is described by the following exponential model:

The time constant for the isotope is:


The mass of the isotope after 276 days is:


Answer:
15
Step-by-step explanation:
Coefficient means the number in front of the variable (like r) or term (a letter).
In your expression 3-15r, 15 is the coefficient.
I hope this helps.
The answer is 12 but the way you get it is you subtract 400 from 1000 which gives you 600 then you divide 600 by 50 to get 12. So it looks like this 1000-400= 600, 600/50=12. Hope this helps. :)
Answer:
mmm, well, not much we can do per se, you'd need to use a calculator.
I'd like to point out you'd need a calculator that has regression features, namely something like a TI83 or TI83+ or higher.
That said, you can find online calculators with "quadratic regression" features, which is what this, all you do is enter the value pairs in it, to get the equation.
Step-by-step explanation: