(iii) Find
t
so that
N
=
2
N
0
.
The value of
N
is the y intercept of the line of best fit. These values
0
from the curve of best fit are not directly accessible but can be retrieved
using the
PREDY
function (see page 135). This is shown in the screen
shown right. Store the results into memories
A
and
K
. This saves having
to re-type them from the
screen.
Now switch to the Solve aplet and enter the equation to be solved.
Changing into the
NUM
view, you should find the values of A and K
already defined (that was why we stored the curve values into the
appropriate memories), so move the highlight to T and press
.
Result: Doubling time is 1.0536 hours.
Note: An alternative to this would be to only retrieve the value of
N
0
and store it into
A
. The Solve equation could then be
PREDY(T)=2*A
and the result would be the
same.
140