2 Short answer questions (1 Viewer)

[rabdog]

http://img92.exs.cx/my.php?loc=img9...=methods8jg.jpg

this is the image with the questions on it...
please provide solutions

sorry here is the link that works:

http://img92.exs.cx/my.php?loc=img92&image=methods8jg.jpg

 

[Ghost1788]

your link is not working.....

 

[rabdog]

bump~~~~~~!

 

[KFunk]

1. a)
at t=0 ---> M_oe^-kt=10 so M_o=10
at t=140:
5=10e^-140k
ln(1/2)=ln(e^-140k)
-ln(1/2)/140= k so k = 4.95 x10^-3 to 2d.p.


b) After 70 days M = 10e^-70k = 7.07 grams

c) 2= 10e^-kt
1/5 = e^-kt
ln(1/5) = -kt
t = -ln(1/5)/k = 325.07 days to 2d.p.

 

[rabdog]

thanks for that, can anyone help with number 2?

 

[JamiL]

no1 is 2u mate...