Guys. Help me with a Math Problem.

[FSANE]

You will need a Scientific Calculator for this.


An exponential decay function that can be used to model the amount of Carbon-14 that remains after a period of time is given below:

Y=280e^(-0.00012378t) grams

Where "Y" is the amount of Carbon-14 remaining after "t" years (in grams).

Set up Windows: Xmin=0, Xmax=25000, Ymin=0, Ymax=100


Here are the 2 questions:

Question #1


How much Carbon-14 (to the nearest gram) will remain after 1500 years?

X=______ Y=______


Question #2

The Half-life is the number of years it takes for a substance to decay to half of its original mass (or weight). Use the intersection method to calculate the half-life of Carbon-14. Round off to the nearest year.

X=________ Y=________





Ok I am stuck, no idea what the answers are. and for the question #2. half-life of year "0" or year "1500"?

Thanks.

[toi tyme]

oooh bio chem.... ill try to work it through.

[ss~zoso~ss]

assuming you start with 100 grams of C;

for number 1, t = x = 1500 and Y = the answer when you plug in 1500 for t

for number 2 Y = 50 or set a function Y=50 and find where it intersects with your decay function

this should hopefully help, any other viewers; post up if i made a mistake
im in the midst of procrastinating with engineering work.

[pajeff02]

Maybe I am missing something, but how many grams of Carbon 14 are we starting with? After 1,500 years, there would be 83.406% of the original Carbon 14 remaining...

[ss~zoso~ss]

right, i assumed since he was told to set the window Y max at 100, it can either be 100 grams, or 100 percent start, thus a direct conversion from percentage to grams

[FSANE]

No at the start year 0 is 280 grams

[67CamaroRSSS]

If I started with 100 grams of "C" it wouldn't have much of a half life.

On the other hand I'd be the life of the party for awhile.....

[TransAm11973]

If I started with 100 grams of "C" it wouldn't have much of a half life.

On the other hand I'd be the life of the party for awhile.....

[nuttyprofessor]

assuming you start with 100 grams of C;

for number 1, t = x = 1500 and Y = the answer when you plug in 1500 for t

for number 2 Y = 50 or set a function Y=50 and find where it intersects with your decay function

this should hopefully help, any other viewers; post up if i made a mistake
im in the midst of procrastinating with engineering work.

Assuming your equation is right and your min/max values are not written correctly

Almost right....if you plug in t=0 you get 280 as your starting mass. Therefore at t=1500yrs you get 232.5533 grams remaining.

Then you would need to determine what t will equal when Y= 140 grams. so you can rearrange the equation and solve for t. or you can graph the equation as it is written and determine where Y=140 and look at the X value. X = 5600 yrs when you round up. Equation would be ((LN(140/280))/(-0.00012378)) which equals 5599.832 years

BTW don't need a graphing calculator...use excel

[ebdboudreaux]

O this was so my forte last semester... However, once i stop using it.. its gone... haha... Good luck

[ss~zoso~ss]

Assuming your equation is right and your min/max values are not written correctly

Almost right....if you plug in t=0 you get 280 as your starting mass. Therefore at t=1500yrs you get 232.5533 grams remaining.

Then you would need to determine what t will equal when Y= 140 grams. so you can rearrange the equation and solve for t. or you can graph the equation as it is written and determine where Y=140 and look at the X value. X = 5600 yrs when you round up. Equation would be ((LN(140/280))/(-0.00012378)) which equals 5599.832 years

BTW don't need a graphing calculator...use excel

yea I forgot, the 280 is the Yo amount ...

[FSANE]

Thanks dudes!

[0rion]

that's simple....the answer is 7

[toi tyme]

Yeah I havent done half life yet.. haha So your guess is as good as mine! haha

[Nhra Firebird]

that's simple....the answer is 7

coming from the guy that wanted to know how many gallons of water it takes to fill his pool

[grouch0jr]

Yeah I havent done half life yet.. haha So your guess is as good as mine! haha

never ask a girl for help with math