the half-life of rhodium rh-106 is about 30 seconds. you start with 500 grams.

formula: y=ab^x

3 answers

after x seconds, you will have
y = 500(1/2)^(x/30)
but that does not quite fit the required formula. So, what to do?

y = 500*((1/2)^1/30)^x = 500*0.97716^x
We were not supposed to solve. Just find the equation. Should have wrote equation instead of formula.
Why is the x divided by 30 as opposed to say multiplied by 30?
every 30 seconds the amount is reduced by half. That is, 1/2 is raised to one higher power.

If it was cut in half every second, the formula would be (1/2)^x
but x has to increase by a factor of 30 to get to the next power of 1/2