Thread: half life solving initial quantity

half life: 1620, initial quantity:x, amount after 1000 years:1.5 g

I need to solve for the initial quantity with the info given, thx for the help

Originally Posted by theman

half life: 1620, initial quantity:x, amount after 1000 years:1.5 g

I need to solve for the initial quantity with the info given, thx for the help

we use the equation

where is the rate of decay, is the amount at time , is the intial amount (what we are searching for).

now,

you know the half-life, so you can find .

once you have . plug in , , and whatever. and solve for

thanks, but i still dun know how to solve for the rate of the decay...

Originally Posted by Jhevon

now,

you know the half-life, so you can find .

Originally Posted by theman

thanks, but i still dun know how to solve for the rate of the decay...

You can't solve that equation for r??

-Dan

lol, sorry, im kinda stupid, but i just solved it thanks!

um, sorry, but one more thing. With the same info and the initial quantity i got was 2.3 g. How would u solve it for 10,000 years.

Originally Posted by theman

um, sorry, but one more thing. With the same info and the initial quantity i got was 2.3 g. How would u solve it for 10,000 years.

You have and r. Just plug in t = 10000 years.

-Dan

Originally Posted by theman

half life: 1620, initial quantity:x, amount after 1000 years:1.5 g

I need to solve for the initial quantity with the info given, thx for the help

double posts .